diff --git a/README.md b/README.md
index 0d34890..b13b1a3 100644
--- a/README.md
+++ b/README.md
@@ -41,9 +41,9 @@ A parser library for System Verilog.
 | instantiations                    | program_instantiation                 | x    | x      |      |
 | instantiations                    | checker_instantiation                 | x    | x      |      |
 | instantiations                    | generated_instantiation               | x    | x      |      |
-| udp_declaration_and_instantiation | udp_declaration                       |      |        |      |
-| udp_declaration_and_instantiation | udp_ports                             |      |        |      |
-| udp_declaration_and_instantiation | udp_body                              |      |        |      |
+| udp_declaration_and_instantiation | udp_declaration                       | x    | x      |      |
+| udp_declaration_and_instantiation | udp_ports                             | x    | x      |      |
+| udp_declaration_and_instantiation | udp_body                              | x    | x      |      |
 | udp_declaration_and_instantiation | udp_instantiation                     | x    | x      |      |
 | behavioral_statements             | continuous_assignment_and_net_alias   | x    | x      |      |
 | behavioral_statements             | procedural_blocks_and_assignments     | x    | x      |      |
@@ -58,13 +58,13 @@ A parser library for System Verilog.
 | behavioral_statements             | assertion_statements                  | x    | x      |      |
 | behavioral_statements             | clocking_block                        | x    | x      |      |
 | behavioral_statements             | randsequence                          | x    | x      |      |
-| specify_section                   | specify_block_declaration             |      |        |      |
-| specify_section                   | specify_path_declarations             |      |        |      |
-| specify_section                   | specify_block_terminals               |      |        |      |
-| specify_section                   | specify_path_delays                   |      |        |      |
-| specify_section                   | system_timing_check_commands          |      |        |      |
-| specify_section                   | system_timing_check_command_arguments |      |        |      |
-| specify_section                   | system_timing_check_event_definitions |      |        |      |
+| specify_section                   | specify_block_declaration             | x    | x      |      |
+| specify_section                   | specify_path_declarations             | x    | x      |      |
+| specify_section                   | specify_block_terminals               | x    | x      |      |
+| specify_section                   | specify_path_delays                   | x    | x      |      |
+| specify_section                   | system_timing_check_commands          | x    | x      |      |
+| specify_section                   | system_timing_check_command_arguments | x    | x      |      |
+| specify_section                   | system_timing_check_event_definitions | x    | x      |      |
 | expressions                       | concatenations                        | x    | x      |      |
 | expressions                       | subroutine_calls                      | x    | x      |      |
 | expressions                       | expressions                           | x    | x      |      |
@@ -76,3 +76,8 @@ A parser library for System Verilog.
 | general                           | attributes                            | x    | x      | x    |
 | general                           | comments                              | x    | x      | x    |
 | general                           | identifiers                           | x    | x      | x    |
+
+## TODO
+
+* Exclude reserved keyword from identifiers.
+* Implement ambiguous_alt for varirble_port_type.
diff --git a/src/parser/specify_section/mod.rs b/src/parser/specify_section/mod.rs
index 4c4eb12..0921b9d 100644
--- a/src/parser/specify_section/mod.rs
+++ b/src/parser/specify_section/mod.rs
@@ -1,6 +1,14 @@
 pub mod specify_block_declaration;
 pub mod specify_block_terminals;
+pub mod specify_path_declarations;
 pub mod specify_path_delays;
+pub mod system_timing_check_command_arguments;
+pub mod system_timing_check_commands;
+pub mod system_timing_check_event_definitions;
 pub use specify_block_declaration::*;
 pub use specify_block_terminals::*;
+pub use specify_path_declarations::*;
 pub use specify_path_delays::*;
+pub use system_timing_check_command_arguments::*;
+pub use system_timing_check_commands::*;
+pub use system_timing_check_event_definitions::*;
diff --git a/src/parser/specify_section/specify_block_declaration.rs b/src/parser/specify_section/specify_block_declaration.rs
index 810e57a..49bdcd0 100644
--- a/src/parser/specify_section/specify_block_declaration.rs
+++ b/src/parser/specify_section/specify_block_declaration.rs
@@ -1,20 +1,75 @@
 use crate::ast::*;
 use crate::parser::*;
-//use nom::branch::*;
-//use nom::combinator::*;
-use nom::error::*;
-use nom::{Err, IResult};
+use nom::branch::*;
+use nom::combinator::*;
+use nom::multi::*;
+use nom::IResult;
 
 // -----------------------------------------------------------------------------
 
 #[derive(Debug, Node)]
 pub struct SpecifyBlock<'a> {
-    pub nodes: (Identifier<'a>,),
+    pub nodes: (Symbol<'a>, Vec<SpecifyItem<'a>>, Symbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub enum SpecifyItem<'a> {
+    SpecparamDeclaration(SpecparamDeclaration<'a>),
+    PulsestyleDeclaration(PulsestyleDeclaration<'a>),
+    ShowcancelledDeclaration(ShowcancelledDeclaration<'a>),
+    PathDeclaration(PathDeclaration<'a>),
+    SystemTimingCheck(SystemTimingCheck<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct PulsestyleDeclaration<'a> {
+    pub nodes: (Symbol<'a>, ListOfPathOutputs<'a>, Symbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct ShowcancelledDeclaration<'a> {
+    pub nodes: (Symbol<'a>, ListOfPathOutputs<'a>, Symbol<'a>),
 }
 
 // -----------------------------------------------------------------------------
 
 #[parser]
 pub fn specify_block(s: Span) -> IResult<Span, SpecifyBlock> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+    let (s, a) = symbol("specify")(s)?;
+    let (s, b) = many0(specify_item)(s)?;
+    let (s, c) = symbol("endspecify")(s)?;
+    Ok((s, SpecifyBlock { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn specify_item(s: Span) -> IResult<Span, SpecifyItem> {
+    alt((
+        map(specparam_declaration, |x| {
+            SpecifyItem::SpecparamDeclaration(x)
+        }),
+        map(pulsestyle_declaration, |x| {
+            SpecifyItem::PulsestyleDeclaration(x)
+        }),
+        map(showcancelled_declaration, |x| {
+            SpecifyItem::ShowcancelledDeclaration(x)
+        }),
+        map(path_declaration, |x| SpecifyItem::PathDeclaration(x)),
+        map(system_timing_check, |x| SpecifyItem::SystemTimingCheck(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn pulsestyle_declaration(s: Span) -> IResult<Span, PulsestyleDeclaration> {
+    let (s, a) = alt((symbol("pulsestyle_onevent"), symbol("pulsestyle_ondetect")))(s)?;
+    let (s, b) = list_of_path_outputs(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, PulsestyleDeclaration { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn showcancelled_declaration(s: Span) -> IResult<Span, ShowcancelledDeclaration> {
+    let (s, a) = alt((symbol("showcalcelled"), symbol("noshowcancelled")))(s)?;
+    let (s, b) = list_of_path_outputs(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, ShowcancelledDeclaration { nodes: (a, b, c) }))
 }
diff --git a/src/parser/specify_section/specify_block_terminals.rs b/src/parser/specify_section/specify_block_terminals.rs
index 8f0022e..9708b81 100644
--- a/src/parser/specify_section/specify_block_terminals.rs
+++ b/src/parser/specify_section/specify_block_terminals.rs
@@ -1,20 +1,25 @@
 use crate::ast::*;
 use crate::parser::*;
-//use nom::branch::*;
-//use nom::combinator::*;
-use nom::error::*;
-use nom::{Err, IResult};
+use nom::branch::*;
+use nom::combinator::*;
+use nom::IResult;
 
 // -----------------------------------------------------------------------------
 
 #[derive(Debug, Node)]
 pub struct SpecifyInputTerminalDescriptor<'a> {
-    pub nodes: (InputIdentifier<'a>, Option<ConstantRangeExpression<'a>>),
+    pub nodes: (
+        InputIdentifier<'a>,
+        Option<Bracket<'a, ConstantRangeExpression<'a>>>,
+    ),
 }
 
 #[derive(Debug, Node)]
 pub struct SpecifyOutputTerminalDescriptor<'a> {
-    pub nodes: (OutputIdentifier<'a>, Option<ConstantRangeExpression<'a>>),
+    pub nodes: (
+        OutputIdentifier<'a>,
+        Option<Bracket<'a, ConstantRangeExpression<'a>>>,
+    ),
 }
 
 #[derive(Debug, Node)]
@@ -26,7 +31,7 @@ pub enum InputIdentifier<'a> {
 
 #[derive(Debug, Node)]
 pub struct InputIdentifierInterface<'a> {
-    pub nodes: (InterfaceIdentifier<'a>, PortIdentifier<'a>),
+    pub nodes: (InterfaceIdentifier<'a>, Symbol<'a>, PortIdentifier<'a>),
 }
 
 #[derive(Debug, Node)]
@@ -38,29 +43,71 @@ pub enum OutputIdentifier<'a> {
 
 #[derive(Debug, Node)]
 pub struct OutputIdentifierInterface<'a> {
-    pub nodes: (InterfaceIdentifier<'a>, PortIdentifier<'a>),
+    pub nodes: (InterfaceIdentifier<'a>, Symbol<'a>, PortIdentifier<'a>),
 }
 
 // -----------------------------------------------------------------------------
 
 #[parser]
 pub fn specify_input_terminal_descriptor(s: Span) -> IResult<Span, SpecifyInputTerminalDescriptor> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+    let (s, a) = input_identifier(s)?;
+    let (s, b) = opt(bracket(constant_range_expression))(s)?;
+    Ok((s, SpecifyInputTerminalDescriptor { nodes: (a, b) }))
 }
 
 #[parser]
 pub fn specify_output_terminal_descriptor(
     s: Span,
 ) -> IResult<Span, SpecifyOutputTerminalDescriptor> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+    let (s, a) = output_identifier(s)?;
+    let (s, b) = opt(bracket(constant_range_expression))(s)?;
+    Ok((s, SpecifyOutputTerminalDescriptor { nodes: (a, b) }))
 }
 
 #[parser]
 pub fn input_identifier(s: Span) -> IResult<Span, InputIdentifier> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+    alt((
+        map(input_port_identifier, |x| {
+            InputIdentifier::InputPortIdentifier(x)
+        }),
+        map(inout_port_identifier, |x| {
+            InputIdentifier::InoutPortIdentifier(x)
+        }),
+        input_identifier_interface,
+    ))(s)
+}
+
+#[parser]
+pub fn input_identifier_interface(s: Span) -> IResult<Span, InputIdentifier> {
+    let (s, a) = interface_identifier(s)?;
+    let (s, b) = symbol(".")(s)?;
+    let (s, c) = port_identifier(s)?;
+    Ok((
+        s,
+        InputIdentifier::Interface(InputIdentifierInterface { nodes: (a, b, c) }),
+    ))
 }
 
 #[parser]
 pub fn output_identifier(s: Span) -> IResult<Span, OutputIdentifier> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+    alt((
+        map(output_port_identifier, |x| {
+            OutputIdentifier::OutputPortIdentifier(x)
+        }),
+        map(inout_port_identifier, |x| {
+            OutputIdentifier::InoutPortIdentifier(x)
+        }),
+        output_identifier_interface,
+    ))(s)
+}
+
+#[parser]
+pub fn output_identifier_interface(s: Span) -> IResult<Span, OutputIdentifier> {
+    let (s, a) = interface_identifier(s)?;
+    let (s, b) = symbol(".")(s)?;
+    let (s, c) = port_identifier(s)?;
+    Ok((
+        s,
+        OutputIdentifier::Interface(OutputIdentifierInterface { nodes: (a, b, c) }),
+    ))
 }
diff --git a/src/parser/specify_section/specify_path_declarations.rs b/src/parser/specify_section/specify_path_declarations.rs
new file mode 100644
index 0000000..50a8024
--- /dev/null
+++ b/src/parser/specify_section/specify_path_declarations.rs
@@ -0,0 +1,152 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::sequence::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub enum PathDeclaration<'a> {
+    SimplePathDeclaration((SimplePathDeclaration<'a>, Symbol<'a>)),
+    EdgeSensitivePathDeclaration((EdgeSensitivePathDeclaration<'a>, Symbol<'a>)),
+    StateDependentPathDeclaration((StateDependentPathDeclaration<'a>, Symbol<'a>)),
+}
+
+#[derive(Debug, Node)]
+pub enum SimplePathDeclaration<'a> {
+    Parallel(SimplePathDeclarationParallel<'a>),
+    Full(SimplePathDeclarationFull<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct SimplePathDeclarationParallel<'a> {
+    pub nodes: (ParallelPathDescription<'a>, Symbol<'a>, PathDelayValue<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct SimplePathDeclarationFull<'a> {
+    pub nodes: (FullPathDescription<'a>, Symbol<'a>, PathDelayValue<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct ParallelPathDescription<'a> {
+    pub nodes: (
+        Paren<
+            'a,
+            (
+                SpecifyInputTerminalDescriptor<'a>,
+                Option<PolarityOperator<'a>>,
+                Symbol<'a>,
+                SpecifyOutputTerminalDescriptor<'a>,
+            ),
+        >,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct FullPathDescription<'a> {
+    pub nodes: (
+        Paren<
+            'a,
+            (
+                ListOfPathInputs<'a>,
+                Option<PolarityOperator<'a>>,
+                Symbol<'a>,
+                ListOfPathOutputs<'a>,
+            ),
+        >,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct ListOfPathInputs<'a> {
+    pub nodes: (List<Symbol<'a>, SpecifyInputTerminalDescriptor<'a>>,),
+}
+
+#[derive(Debug, Node)]
+pub struct ListOfPathOutputs<'a> {
+    pub nodes: (List<Symbol<'a>, SpecifyOutputTerminalDescriptor<'a>>,),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn path_declaration(s: Span) -> IResult<Span, PathDeclaration> {
+    alt((
+        map(pair(simple_path_declaration, symbol(";")), |x| {
+            PathDeclaration::SimplePathDeclaration(x)
+        }),
+        map(pair(edge_sensitive_path_declaration, symbol(";")), |x| {
+            PathDeclaration::EdgeSensitivePathDeclaration(x)
+        }),
+        map(pair(state_dependent_path_declaration, symbol(";")), |x| {
+            PathDeclaration::StateDependentPathDeclaration(x)
+        }),
+    ))(s)
+}
+
+#[parser]
+pub fn simple_path_declaration(s: Span) -> IResult<Span, SimplePathDeclaration> {
+    alt((
+        simple_path_declaration_parallel,
+        simple_path_declaration_full,
+    ))(s)
+}
+
+#[parser]
+pub fn simple_path_declaration_parallel(s: Span) -> IResult<Span, SimplePathDeclaration> {
+    let (s, a) = parallel_path_description(s)?;
+    let (s, b) = symbol("=")(s)?;
+    let (s, c) = path_delay_value(s)?;
+    Ok((
+        s,
+        SimplePathDeclaration::Parallel(SimplePathDeclarationParallel { nodes: (a, b, c) }),
+    ))
+}
+
+#[parser]
+pub fn simple_path_declaration_full(s: Span) -> IResult<Span, SimplePathDeclaration> {
+    let (s, a) = full_path_description(s)?;
+    let (s, b) = symbol("=")(s)?;
+    let (s, c) = path_delay_value(s)?;
+    Ok((
+        s,
+        SimplePathDeclaration::Full(SimplePathDeclarationFull { nodes: (a, b, c) }),
+    ))
+}
+
+#[parser]
+pub fn parallel_path_description(s: Span) -> IResult<Span, ParallelPathDescription> {
+    let (s, a) = paren(tuple((
+        specify_input_terminal_descriptor,
+        opt(polarity_operator),
+        symbol("=>"),
+        specify_output_terminal_descriptor,
+    )))(s)?;
+    Ok((s, ParallelPathDescription { nodes: (a,) }))
+}
+
+#[parser]
+pub fn full_path_description(s: Span) -> IResult<Span, FullPathDescription> {
+    let (s, a) = paren(tuple((
+        list_of_path_inputs,
+        opt(polarity_operator),
+        symbol("*>"),
+        list_of_path_outputs,
+    )))(s)?;
+    Ok((s, FullPathDescription { nodes: (a,) }))
+}
+
+#[parser]
+pub fn list_of_path_inputs(s: Span) -> IResult<Span, ListOfPathInputs> {
+    let (s, a) = list(symbol(","), specify_input_terminal_descriptor)(s)?;
+    Ok((s, ListOfPathInputs { nodes: (a,) }))
+}
+
+#[parser]
+pub fn list_of_path_outputs(s: Span) -> IResult<Span, ListOfPathOutputs> {
+    let (s, a) = list(symbol(","), specify_output_terminal_descriptor)(s)?;
+    Ok((s, ListOfPathOutputs { nodes: (a,) }))
+}
diff --git a/src/parser/specify_section/specify_path_delays.rs b/src/parser/specify_section/specify_path_delays.rs
index 9d3b63e..3f111e8 100644
--- a/src/parser/specify_section/specify_path_delays.rs
+++ b/src/parser/specify_section/specify_path_delays.rs
@@ -1,20 +1,341 @@
 use crate::ast::*;
 use crate::parser::*;
-//use nom::branch::*;
-//use nom::combinator::*;
-use nom::error::*;
-use nom::{Err, IResult};
+use nom::branch::*;
+use nom::combinator::*;
+use nom::sequence::*;
+use nom::IResult;
 
 // -----------------------------------------------------------------------------
 
 #[derive(Debug, Node)]
-pub struct EdgeIdentifier<'a> {
-    pub nodes: (Identifier<'a>,),
+pub enum PathDelayValue<'a> {
+    ListOfPathDelayExpressions(ListOfPathDelayExpressions<'a>),
+    Paren(PathDelayValueParen<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct PathDelayValueParen<'a> {
+    pub nodes: (Paren<'a, ListOfPathDelayExpressions<'a>>,),
+}
+
+#[derive(Debug, Node)]
+pub struct ListOfPathDelayExpressions<'a> {
+    pub nodes: (List<Symbol<'a>, TPathDelayExpression<'a>>,),
+}
+
+#[derive(Debug, Node)]
+pub struct TPathDelayExpression<'a> {
+    pub nodes: (PathDelayExpression<'a>,),
+}
+#[derive(Debug, Node)]
+pub struct PathDelayExpression<'a> {
+    pub nodes: (ConstantMintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub enum EdgeSensitivePathDeclaration<'a> {
+    Parallel(EdgeSensitivePathDeclarationParallel<'a>),
+    Full(EdgeSensitivePathDeclarationFull<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeSensitivePathDeclarationParallel<'a> {
+    pub nodes: (
+        ParallelEdgeSensitivePathDescription<'a>,
+        Symbol<'a>,
+        PathDelayValue<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeSensitivePathDeclarationFull<'a> {
+    pub nodes: (
+        FullEdgeSensitivePathDescription<'a>,
+        Symbol<'a>,
+        PathDelayValue<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct ParallelEdgeSensitivePathDescription<'a> {
+    pub nodes: (
+        Paren<
+            'a,
+            (
+                Option<EdgeIdentifier<'a>>,
+                SpecifyInputTerminalDescriptor<'a>,
+                Option<PolarityOperator<'a>>,
+                Symbol<'a>,
+                Paren<
+                    'a,
+                    (
+                        SpecifyOutputTerminalDescriptor<'a>,
+                        Option<PolarityOperator<'a>>,
+                        Symbol<'a>,
+                        DataSourceExpression<'a>,
+                    ),
+                >,
+            ),
+        >,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct FullEdgeSensitivePathDescription<'a> {
+    pub nodes: (
+        Paren<
+            'a,
+            (
+                Option<EdgeIdentifier<'a>>,
+                ListOfPathInputs<'a>,
+                Option<PolarityOperator<'a>>,
+                Symbol<'a>,
+                Paren<
+                    'a,
+                    (
+                        ListOfPathOutputs<'a>,
+                        Option<PolarityOperator<'a>>,
+                        Symbol<'a>,
+                        DataSourceExpression<'a>,
+                    ),
+                >,
+            ),
+        >,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct DataSourceExpression<'a> {
+    pub nodes: (Expression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub enum EdgeIdentifier<'a> {
+    Posedge(Symbol<'a>),
+    Negedge(Symbol<'a>),
+    Edge(Symbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub enum StateDependentPathDeclaration<'a> {
+    IfSimple(StateDependentPathDeclarationIfSimple<'a>),
+    IfEdgeSensitive(StateDependentPathDeclarationIfEdgeSensitive<'a>),
+    IfNone(StateDependentPathDeclarationIfNone<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct StateDependentPathDeclarationIfSimple<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<'a, ModulePathExpression<'a>>,
+        SimplePathDeclaration<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct StateDependentPathDeclarationIfEdgeSensitive<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<'a, ModulePathExpression<'a>>,
+        EdgeSensitivePathDeclaration<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct StateDependentPathDeclarationIfNone<'a> {
+    pub nodes: (Symbol<'a>, SimplePathDeclaration<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct PolarityOperator<'a> {
+    pub nodes: (Symbol<'a>,),
 }
 
 // -----------------------------------------------------------------------------
 
 #[parser]
-pub fn edge_identifier(s: Span) -> IResult<Span, EdgeIdentifier> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+pub fn path_delay_value(s: Span) -> IResult<Span, PathDelayValue> {
+    alt((
+        map(list_of_path_delay_expressions, |x| {
+            PathDelayValue::ListOfPathDelayExpressions(x)
+        }),
+        path_delay_value_paren,
+    ))(s)
+}
+
+#[parser]
+pub fn path_delay_value_paren(s: Span) -> IResult<Span, PathDelayValue> {
+    let (s, a) = paren(list_of_path_delay_expressions)(s)?;
+    Ok((
+        s,
+        PathDelayValue::Paren(PathDelayValueParen { nodes: (a,) }),
+    ))
+}
+
+#[parser]
+pub fn list_of_path_delay_expressions(s: Span) -> IResult<Span, ListOfPathDelayExpressions> {
+    let (s, a) = list(symbol(","), t_path_delay_expression)(s)?;
+    Ok((s, ListOfPathDelayExpressions { nodes: (a,) }))
+}
+
+#[parser]
+pub fn t_path_delay_expression(s: Span) -> IResult<Span, TPathDelayExpression> {
+    let (s, a) = path_delay_expression(s)?;
+    Ok((s, TPathDelayExpression { nodes: (a,) }))
+}
+
+#[parser]
+pub fn path_delay_expression(s: Span) -> IResult<Span, PathDelayExpression> {
+    let (s, a) = constant_mintypmax_expression(s)?;
+    Ok((s, PathDelayExpression { nodes: (a,) }))
+}
+
+#[parser]
+pub fn edge_sensitive_path_declaration(s: Span) -> IResult<Span, EdgeSensitivePathDeclaration> {
+    alt((
+        edge_sensitive_path_declaration_parallel,
+        edge_sensitive_path_declaration_full,
+    ))(s)
+}
+
+#[parser]
+pub fn edge_sensitive_path_declaration_parallel(
+    s: Span,
+) -> IResult<Span, EdgeSensitivePathDeclaration> {
+    let (s, a) = parallel_edge_sensitive_path_description(s)?;
+    let (s, b) = symbol("=")(s)?;
+    let (s, c) = path_delay_value(s)?;
+    Ok((
+        s,
+        EdgeSensitivePathDeclaration::Parallel(EdgeSensitivePathDeclarationParallel {
+            nodes: (a, b, c),
+        }),
+    ))
+}
+
+#[parser]
+pub fn edge_sensitive_path_declaration_full(
+    s: Span,
+) -> IResult<Span, EdgeSensitivePathDeclaration> {
+    let (s, a) = full_edge_sensitive_path_description(s)?;
+    let (s, b) = symbol("=")(s)?;
+    let (s, c) = path_delay_value(s)?;
+    Ok((
+        s,
+        EdgeSensitivePathDeclaration::Full(EdgeSensitivePathDeclarationFull { nodes: (a, b, c) }),
+    ))
+}
+
+#[parser]
+pub fn parallel_edge_sensitive_path_description(
+    s: Span,
+) -> IResult<Span, ParallelEdgeSensitivePathDescription> {
+    let (s, a) = paren(tuple((
+        opt(edge_identifier),
+        specify_input_terminal_descriptor,
+        opt(polarity_operator),
+        symbol("=>"),
+        paren(tuple((
+            specify_output_terminal_descriptor,
+            opt(polarity_operator),
+            symbol(":"),
+            data_source_expression,
+        ))),
+    )))(s)?;
+    Ok((s, ParallelEdgeSensitivePathDescription { nodes: (a,) }))
+}
+
+#[parser]
+pub fn full_edge_sensitive_path_description(
+    s: Span,
+) -> IResult<Span, FullEdgeSensitivePathDescription> {
+    let (s, a) = paren(tuple((
+        opt(edge_identifier),
+        list_of_path_inputs,
+        opt(polarity_operator),
+        symbol("*>"),
+        paren(tuple((
+            list_of_path_outputs,
+            opt(polarity_operator),
+            symbol(":"),
+            data_source_expression,
+        ))),
+    )))(s)?;
+    Ok((s, FullEdgeSensitivePathDescription { nodes: (a,) }))
+}
+
+#[parser]
+pub fn data_source_expression(s: Span) -> IResult<Span, DataSourceExpression> {
+    let (s, a) = expression(s)?;
+    Ok((s, DataSourceExpression { nodes: (a,) }))
+}
+
+#[parser]
+pub fn edge_identifier(s: Span) -> IResult<Span, EdgeIdentifier> {
+    alt((
+        map(symbol("posedge"), |x| EdgeIdentifier::Posedge(x)),
+        map(symbol("negedge"), |x| EdgeIdentifier::Negedge(x)),
+        map(symbol("edge"), |x| EdgeIdentifier::Edge(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn state_dependent_path_declaration(s: Span) -> IResult<Span, StateDependentPathDeclaration> {
+    alt((
+        state_dependent_path_declaration_if_simple,
+        state_dependent_path_declaration_if_edge_sensitive,
+        state_dependent_path_declaration_if_none,
+    ))(s)
+}
+
+#[parser]
+pub fn state_dependent_path_declaration_if_simple(
+    s: Span,
+) -> IResult<Span, StateDependentPathDeclaration> {
+    let (s, a) = symbol("if")(s)?;
+    let (s, b) = paren(module_path_expression)(s)?;
+    let (s, c) = simple_path_declaration(s)?;
+    Ok((
+        s,
+        StateDependentPathDeclaration::IfSimple(StateDependentPathDeclarationIfSimple {
+            nodes: (a, b, c),
+        }),
+    ))
+}
+
+#[parser]
+pub fn state_dependent_path_declaration_if_edge_sensitive(
+    s: Span,
+) -> IResult<Span, StateDependentPathDeclaration> {
+    let (s, a) = symbol("if")(s)?;
+    let (s, b) = paren(module_path_expression)(s)?;
+    let (s, c) = edge_sensitive_path_declaration(s)?;
+    Ok((
+        s,
+        StateDependentPathDeclaration::IfEdgeSensitive(
+            StateDependentPathDeclarationIfEdgeSensitive { nodes: (a, b, c) },
+        ),
+    ))
+}
+
+#[parser]
+pub fn state_dependent_path_declaration_if_none(
+    s: Span,
+) -> IResult<Span, StateDependentPathDeclaration> {
+    let (s, a) = symbol("ifnone")(s)?;
+    let (s, b) = simple_path_declaration(s)?;
+    Ok((
+        s,
+        StateDependentPathDeclaration::IfNone(StateDependentPathDeclarationIfNone {
+            nodes: (a, b),
+        }),
+    ))
+}
+
+#[parser]
+pub fn polarity_operator(s: Span) -> IResult<Span, PolarityOperator> {
+    alt((
+        map(symbol("+"), |x| PolarityOperator { nodes: (x,) }),
+        map(symbol("-"), |x| PolarityOperator { nodes: (x,) }),
+    ))(s)
 }
diff --git a/src/parser/specify_section/system_timing_check_command_arguments.rs b/src/parser/specify_section/system_timing_check_command_arguments.rs
new file mode 100644
index 0000000..4dac4e6
--- /dev/null
+++ b/src/parser/specify_section/system_timing_check_command_arguments.rs
@@ -0,0 +1,207 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub struct TimecheckCondition<'a> {
+    pub nodes: (MintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct ControlledReferenceEvent<'a> {
+    pub nodes: (ControlledTimingCheckEvent<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct DataEvent<'a> {
+    pub nodes: (TimingCheckEvent<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub enum DelayedData<'a> {
+    TerminalIdentifier(TerminalIdentifier<'a>),
+    WithMintypmax(DelayedDataWithMintypmax<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct DelayedDataWithMintypmax<'a> {
+    pub nodes: (
+        TerminalIdentifier<'a>,
+        Bracket<'a, ConstantMintypmaxExpression<'a>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum DelayedReference<'a> {
+    TerminalIdentifier(TerminalIdentifier<'a>),
+    WithMintypmax(DelayedReferenceWithMintypmax<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct DelayedReferenceWithMintypmax<'a> {
+    pub nodes: (
+        TerminalIdentifier<'a>,
+        Bracket<'a, ConstantMintypmaxExpression<'a>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct EndEdgeOffset<'a> {
+    pub nodes: (MintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct EventBasedFlag<'a> {
+    pub nodes: (ConstantExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct Notifier<'a> {
+    pub nodes: (VariableIdentifier<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct ReferenceEvent<'a> {
+    pub nodes: (TimingCheckEvent<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct RemainActiveFlag<'a> {
+    pub nodes: (ConstantMintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct TimestampCondition<'a> {
+    pub nodes: (MintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct StartEdgeOffset<'a> {
+    pub nodes: (MintypmaxExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct Threshold<'a> {
+    pub nodes: (ConstantExpression<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct TimingCheckLimit<'a> {
+    pub nodes: (Expression<'a>,),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn timecheck_condition(s: Span) -> IResult<Span, TimecheckCondition> {
+    let (s, a) = mintypmax_expression(s)?;
+    Ok((s, TimecheckCondition { nodes: (a,) }))
+}
+
+#[parser]
+pub fn controlled_referecne_event(s: Span) -> IResult<Span, ControlledReferenceEvent> {
+    let (s, a) = controlled_timing_check_event(s)?;
+    Ok((s, ControlledReferenceEvent { nodes: (a,) }))
+}
+
+#[parser]
+pub fn data_event(s: Span) -> IResult<Span, DataEvent> {
+    let (s, a) = timing_check_event(s)?;
+    Ok((s, DataEvent { nodes: (a,) }))
+}
+
+#[parser]
+pub fn delayed_data(s: Span) -> IResult<Span, DelayedData> {
+    alt((
+        map(terminal_identifier, |x| DelayedData::TerminalIdentifier(x)),
+        delayed_data_with_mintypmax,
+    ))(s)
+}
+
+#[parser]
+pub fn delayed_data_with_mintypmax(s: Span) -> IResult<Span, DelayedData> {
+    let (s, a) = terminal_identifier(s)?;
+    let (s, b) = bracket(constant_mintypmax_expression)(s)?;
+    Ok((
+        s,
+        DelayedData::WithMintypmax(DelayedDataWithMintypmax { nodes: (a, b) }),
+    ))
+}
+
+#[parser]
+pub fn delayed_reference(s: Span) -> IResult<Span, DelayedReference> {
+    alt((
+        map(terminal_identifier, |x| {
+            DelayedReference::TerminalIdentifier(x)
+        }),
+        delayed_reference_with_mintypmax,
+    ))(s)
+}
+
+#[parser]
+pub fn delayed_reference_with_mintypmax(s: Span) -> IResult<Span, DelayedReference> {
+    let (s, a) = terminal_identifier(s)?;
+    let (s, b) = bracket(constant_mintypmax_expression)(s)?;
+    Ok((
+        s,
+        DelayedReference::WithMintypmax(DelayedReferenceWithMintypmax { nodes: (a, b) }),
+    ))
+}
+
+#[parser]
+pub fn end_edge_offset(s: Span) -> IResult<Span, EndEdgeOffset> {
+    let (s, a) = mintypmax_expression(s)?;
+    Ok((s, EndEdgeOffset { nodes: (a,) }))
+}
+
+#[parser]
+pub fn event_based_flag(s: Span) -> IResult<Span, EventBasedFlag> {
+    let (s, a) = constant_expression(s)?;
+    Ok((s, EventBasedFlag { nodes: (a,) }))
+}
+
+#[parser]
+pub fn notifier(s: Span) -> IResult<Span, Notifier> {
+    let (s, a) = variable_identifier(s)?;
+    Ok((s, Notifier { nodes: (a,) }))
+}
+
+#[parser]
+pub fn referecne_event(s: Span) -> IResult<Span, ReferenceEvent> {
+    let (s, a) = timing_check_event(s)?;
+    Ok((s, ReferenceEvent { nodes: (a,) }))
+}
+
+#[parser]
+pub fn remain_active_flag(s: Span) -> IResult<Span, RemainActiveFlag> {
+    let (s, a) = constant_mintypmax_expression(s)?;
+    Ok((s, RemainActiveFlag { nodes: (a,) }))
+}
+
+#[parser]
+pub fn timestamp_condition(s: Span) -> IResult<Span, TimestampCondition> {
+    let (s, a) = mintypmax_expression(s)?;
+    Ok((s, TimestampCondition { nodes: (a,) }))
+}
+
+#[parser]
+pub fn start_edge_offset(s: Span) -> IResult<Span, StartEdgeOffset> {
+    let (s, a) = mintypmax_expression(s)?;
+    Ok((s, StartEdgeOffset { nodes: (a,) }))
+}
+
+#[parser]
+pub fn threshold(s: Span) -> IResult<Span, Threshold> {
+    let (s, a) = constant_expression(s)?;
+    Ok((s, Threshold { nodes: (a,) }))
+}
+
+#[parser]
+pub fn timing_check_limit(s: Span) -> IResult<Span, TimingCheckLimit> {
+    let (s, a) = expression(s)?;
+    Ok((s, TimingCheckLimit { nodes: (a,) }))
+}
diff --git a/src/parser/specify_section/system_timing_check_commands.rs b/src/parser/specify_section/system_timing_check_commands.rs
new file mode 100644
index 0000000..4ecf558
--- /dev/null
+++ b/src/parser/specify_section/system_timing_check_commands.rs
@@ -0,0 +1,580 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::sequence::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub enum SystemTimingCheck<'a> {
+    SetupTimingCheck(SetupTimingCheck<'a>),
+    HoldTimingCheck(HoldTimingCheck<'a>),
+    SetupholdTimingCheck(SetupholdTimingCheck<'a>),
+    RecoveryTimingCheck(RecoveryTimingCheck<'a>),
+    RemovalTimingCheck(RemovalTimingCheck<'a>),
+    RecremTimingCheck(RecremTimingCheck<'a>),
+    SkewTimingCheck(SkewTimingCheck<'a>),
+    TimeskewTimingCheck(TimeskewTimingCheck<'a>),
+    FullskewTimingCheck(FullskewTimingCheck<'a>),
+    PeriodTimingCheck(PeriodTimingCheck<'a>),
+    WidthTimingCheck(WidthTimingCheck<'a>),
+    NochargeTimingCheck(NochargeTimingCheck<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct SetupTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                DataEvent<'a>,
+                Symbol<'a>,
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct HoldTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct SetupholdTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(
+                    Symbol<'a>,
+                    Option<Notifier<'a>>,
+                    Option<(
+                        Symbol<'a>,
+                        Option<TimestampCondition<'a>>,
+                        Option<(
+                            Symbol<'a>,
+                            Option<TimecheckCondition<'a>>,
+                            Option<(
+                                Symbol<'a>,
+                                Option<DelayedReference<'a>>,
+                                Option<(Symbol<'a>, Option<DelayedData<'a>>)>,
+                            )>,
+                        )>,
+                    )>,
+                )>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct RecoveryTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct RemovalTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct RecremTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(
+                    Symbol<'a>,
+                    Option<Notifier<'a>>,
+                    Option<(
+                        Symbol<'a>,
+                        Option<TimestampCondition<'a>>,
+                        Option<(
+                            Symbol<'a>,
+                            Option<TimecheckCondition<'a>>,
+                            Option<(
+                                Symbol<'a>,
+                                Option<DelayedReference<'a>>,
+                                Option<(Symbol<'a>, Option<DelayedData<'a>>)>,
+                            )>,
+                        )>,
+                    )>,
+                )>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct SkewTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct TimeskewTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(
+                    Symbol<'a>,
+                    Option<Notifier<'a>>,
+                    Option<(
+                        Symbol<'a>,
+                        Option<EventBasedFlag<'a>>,
+                        Option<(Symbol<'a>, Option<RemainActiveFlag<'a>>)>,
+                    )>,
+                )>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct FullskewTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(
+                    Symbol<'a>,
+                    Option<Notifier<'a>>,
+                    Option<(
+                        Symbol<'a>,
+                        Option<EventBasedFlag<'a>>,
+                        Option<(Symbol<'a>, Option<RemainActiveFlag<'a>>)>,
+                    )>,
+                )>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct PeriodTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ControlledReferenceEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct WidthTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ControlledReferenceEvent<'a>,
+                Symbol<'a>,
+                TimingCheckLimit<'a>,
+                Symbol<'a>,
+                Threshold<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct NochargeTimingCheck<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Paren<
+            'a,
+            (
+                ReferenceEvent<'a>,
+                Symbol<'a>,
+                DataEvent<'a>,
+                Symbol<'a>,
+                StartEdgeOffset<'a>,
+                Symbol<'a>,
+                EndEdgeOffset<'a>,
+                Option<(Symbol<'a>, Option<Notifier<'a>>)>,
+            ),
+        >,
+        Symbol<'a>,
+    ),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn system_timing_check(s: Span) -> IResult<Span, SystemTimingCheck> {
+    alt((
+        map(setup_timing_check, |x| {
+            SystemTimingCheck::SetupTimingCheck(x)
+        }),
+        map(hold_timing_check, |x| SystemTimingCheck::HoldTimingCheck(x)),
+        map(setuphold_timing_check, |x| {
+            SystemTimingCheck::SetupholdTimingCheck(x)
+        }),
+        map(recovery_timing_check, |x| {
+            SystemTimingCheck::RecoveryTimingCheck(x)
+        }),
+        map(removal_timing_check, |x| {
+            SystemTimingCheck::RemovalTimingCheck(x)
+        }),
+        map(recrem_timing_check, |x| {
+            SystemTimingCheck::RecremTimingCheck(x)
+        }),
+        map(skew_timing_check, |x| SystemTimingCheck::SkewTimingCheck(x)),
+        map(timeskew_timing_check, |x| {
+            SystemTimingCheck::TimeskewTimingCheck(x)
+        }),
+        map(fullskew_timing_check, |x| {
+            SystemTimingCheck::FullskewTimingCheck(x)
+        }),
+        map(period_timing_check, |x| {
+            SystemTimingCheck::PeriodTimingCheck(x)
+        }),
+        map(width_timing_check, |x| {
+            SystemTimingCheck::WidthTimingCheck(x)
+        }),
+        map(nocharge_timing_check, |x| {
+            SystemTimingCheck::NochargeTimingCheck(x)
+        }),
+    ))(s)
+}
+
+#[parser]
+pub fn setup_timing_check(s: Span) -> IResult<Span, SetupTimingCheck> {
+    let (s, a) = symbol("$setup")(s)?;
+    let (s, b) = paren(tuple((
+        data_event,
+        symbol(","),
+        referecne_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, SetupTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn hold_timing_check(s: Span) -> IResult<Span, HoldTimingCheck> {
+    let (s, a) = symbol("$setup")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, HoldTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn setuphold_timing_check(s: Span) -> IResult<Span, SetupholdTimingCheck> {
+    let (s, a) = symbol("$setuphold")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        symbol(","),
+        timing_check_limit,
+        opt(triple(
+            symbol(","),
+            opt(notifier),
+            opt(triple(
+                symbol(","),
+                opt(timestamp_condition),
+                opt(triple(
+                    symbol(","),
+                    opt(timecheck_condition),
+                    opt(triple(
+                        symbol(","),
+                        opt(delayed_reference),
+                        opt(pair(symbol(","), opt(delayed_data))),
+                    )),
+                )),
+            )),
+        )),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, SetupholdTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn recovery_timing_check(s: Span) -> IResult<Span, RecoveryTimingCheck> {
+    let (s, a) = symbol("$recovery")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, RecoveryTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn removal_timing_check(s: Span) -> IResult<Span, RemovalTimingCheck> {
+    let (s, a) = symbol("$removal")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, RemovalTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn recrem_timing_check(s: Span) -> IResult<Span, RecremTimingCheck> {
+    let (s, a) = symbol("$recrem")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        symbol(","),
+        timing_check_limit,
+        opt(triple(
+            symbol(","),
+            opt(notifier),
+            opt(triple(
+                symbol(","),
+                opt(timestamp_condition),
+                opt(triple(
+                    symbol(","),
+                    opt(timecheck_condition),
+                    opt(triple(
+                        symbol(","),
+                        opt(delayed_reference),
+                        opt(pair(symbol(","), opt(delayed_data))),
+                    )),
+                )),
+            )),
+        )),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, RecremTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn skew_timing_check(s: Span) -> IResult<Span, SkewTimingCheck> {
+    let (s, a) = symbol("$skew")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, SkewTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn timeskew_timing_check(s: Span) -> IResult<Span, TimeskewTimingCheck> {
+    let (s, a) = symbol("$timeskew")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        opt(triple(
+            symbol(","),
+            opt(notifier),
+            opt(triple(
+                symbol(","),
+                opt(event_based_flag),
+                opt(pair(symbol(","), opt(remain_active_flag))),
+            )),
+        )),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, TimeskewTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn fullskew_timing_check(s: Span) -> IResult<Span, FullskewTimingCheck> {
+    let (s, a) = symbol("$fullskew")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        timing_check_limit,
+        symbol(","),
+        timing_check_limit,
+        opt(triple(
+            symbol(","),
+            opt(notifier),
+            opt(triple(
+                symbol(","),
+                opt(event_based_flag),
+                opt(pair(symbol(","), opt(remain_active_flag))),
+            )),
+        )),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, FullskewTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn period_timing_check(s: Span) -> IResult<Span, PeriodTimingCheck> {
+    let (s, a) = symbol("$period")(s)?;
+    let (s, b) = paren(tuple((
+        controlled_referecne_event,
+        symbol(","),
+        timing_check_limit,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, PeriodTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn width_timing_check(s: Span) -> IResult<Span, WidthTimingCheck> {
+    let (s, a) = symbol("$width")(s)?;
+    let (s, b) = paren(tuple((
+        controlled_referecne_event,
+        symbol(","),
+        timing_check_limit,
+        symbol(","),
+        threshold,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, WidthTimingCheck { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn nocharge_timing_check(s: Span) -> IResult<Span, NochargeTimingCheck> {
+    let (s, a) = symbol("$nocharge")(s)?;
+    let (s, b) = paren(tuple((
+        referecne_event,
+        symbol(","),
+        data_event,
+        symbol(","),
+        start_edge_offset,
+        symbol(","),
+        end_edge_offset,
+        opt(pair(symbol(","), opt(notifier))),
+    )))(s)?;
+    let (s, c) = symbol(";")(s)?;
+    Ok((s, NochargeTimingCheck { nodes: (a, b, c) }))
+}
diff --git a/src/parser/specify_section/system_timing_check_event_definitions.rs b/src/parser/specify_section/system_timing_check_event_definitions.rs
new file mode 100644
index 0000000..227ca16
--- /dev/null
+++ b/src/parser/specify_section/system_timing_check_event_definitions.rs
@@ -0,0 +1,224 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::sequence::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub struct TimingCheckEvent<'a> {
+    pub nodes: (
+        Option<TimingCheckEventControl<'a>>,
+        SpecifyTerminalDescriptor<'a>,
+        Option<(Symbol<'a>, TimingCheckCondition<'a>)>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct ControlledTimingCheckEvent<'a> {
+    pub nodes: (
+        TimingCheckEventControl<'a>,
+        SpecifyTerminalDescriptor<'a>,
+        Option<(Symbol<'a>, TimingCheckCondition<'a>)>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum TimingCheckEventControl<'a> {
+    Posedge(Symbol<'a>),
+    Negedge(Symbol<'a>),
+    Edge(Symbol<'a>),
+    EdgeControlSpecifier(EdgeControlSpecifier<'a>),
+}
+
+#[derive(Debug, Node)]
+pub enum SpecifyTerminalDescriptor<'a> {
+    SpecifyInputTerminalDescriptor(SpecifyInputTerminalDescriptor<'a>),
+    SpecifyOutputTerminalDescriptor(SpecifyOutputTerminalDescriptor<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeControlSpecifier<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        Bracket<'a, List<Symbol<'a>, EdgeDescriptor<'a>>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeDescriptor<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub enum TimingCheckCondition<'a> {
+    ScalarTimingCheckCondition(ScalarTimingCheckCondition<'a>),
+    Paren(TimingCheckConditionParen<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct TimingCheckConditionParen<'a> {
+    pub nodes: (Paren<'a, ScalarTimingCheckCondition<'a>>,),
+}
+
+#[derive(Debug, Node)]
+pub enum ScalarTimingCheckCondition<'a> {
+    Expression(Expression<'a>),
+    Unary(ScalarTimingCheckConditionUnary<'a>),
+    Binary(ScalarTimingCheckConditionBinary<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct ScalarTimingCheckConditionUnary<'a> {
+    pub nodes: (Symbol<'a>, Expression<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct ScalarTimingCheckConditionBinary<'a> {
+    pub nodes: (Expression<'a>, Symbol<'a>, ScalarConstant<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct ScalarConstant<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn timing_check_event(s: Span) -> IResult<Span, TimingCheckEvent> {
+    let (s, a) = opt(timing_check_event_control)(s)?;
+    let (s, b) = specify_terminal_descriptor(s)?;
+    let (s, c) = opt(pair(symbol("&&&"), timing_check_condition))(s)?;
+    Ok((s, TimingCheckEvent { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn controlled_timing_check_event(s: Span) -> IResult<Span, ControlledTimingCheckEvent> {
+    let (s, a) = timing_check_event_control(s)?;
+    let (s, b) = specify_terminal_descriptor(s)?;
+    let (s, c) = opt(pair(symbol("&&&"), timing_check_condition))(s)?;
+    Ok((s, ControlledTimingCheckEvent { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn timing_check_event_control(s: Span) -> IResult<Span, TimingCheckEventControl> {
+    alt((
+        map(symbol("posedge"), |x| TimingCheckEventControl::Posedge(x)),
+        map(symbol("negedge"), |x| TimingCheckEventControl::Negedge(x)),
+        map(symbol("edge"), |x| TimingCheckEventControl::Edge(x)),
+        map(edge_control_specifier, |x| {
+            TimingCheckEventControl::EdgeControlSpecifier(x)
+        }),
+    ))(s)
+}
+
+#[parser]
+pub fn specify_terminal_descriptor(s: Span) -> IResult<Span, SpecifyTerminalDescriptor> {
+    alt((
+        map(specify_input_terminal_descriptor, |x| {
+            SpecifyTerminalDescriptor::SpecifyInputTerminalDescriptor(x)
+        }),
+        map(specify_output_terminal_descriptor, |x| {
+            SpecifyTerminalDescriptor::SpecifyOutputTerminalDescriptor(x)
+        }),
+    ))(s)
+}
+
+#[parser]
+pub fn edge_control_specifier(s: Span) -> IResult<Span, EdgeControlSpecifier> {
+    let (s, a) = symbol("edge")(s)?;
+    let (s, b) = bracket(list(symbol(","), edge_descriptor))(s)?;
+    Ok((s, EdgeControlSpecifier { nodes: (a, b) }))
+}
+
+#[parser]
+pub fn edge_descriptor(s: Span) -> IResult<Span, EdgeDescriptor> {
+    alt((
+        map(symbol("01"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("10"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("x0"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("x1"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("X0"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("X1"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("z0"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("z1"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("Z0"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("Z1"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("0x"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("1x"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("0X"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("1X"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("0z"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("1z"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("0Z"), |x| EdgeDescriptor { nodes: (x,) }),
+        map(symbol("1Z"), |x| EdgeDescriptor { nodes: (x,) }),
+    ))(s)
+}
+
+#[parser]
+pub fn timing_check_condition(s: Span) -> IResult<Span, TimingCheckCondition> {
+    alt((
+        map(scalar_timing_check_condition, |x| {
+            TimingCheckCondition::ScalarTimingCheckCondition(x)
+        }),
+        timing_check_condition_paren,
+    ))(s)
+}
+
+#[parser]
+pub fn timing_check_condition_paren(s: Span) -> IResult<Span, TimingCheckCondition> {
+    let (s, a) = paren(scalar_timing_check_condition)(s)?;
+    Ok((
+        s,
+        TimingCheckCondition::Paren(TimingCheckConditionParen { nodes: (a,) }),
+    ))
+}
+
+#[parser]
+pub fn scalar_timing_check_condition(s: Span) -> IResult<Span, ScalarTimingCheckCondition> {
+    alt((
+        map(expression, |x| ScalarTimingCheckCondition::Expression(x)),
+        scalar_timing_check_condition_unary,
+        scalar_timing_check_condition_binary,
+    ))(s)
+}
+
+#[parser]
+pub fn scalar_timing_check_condition_unary(s: Span) -> IResult<Span, ScalarTimingCheckCondition> {
+    let (s, a) = symbol("~")(s)?;
+    let (s, b) = expression(s)?;
+    Ok((
+        s,
+        ScalarTimingCheckCondition::Unary(ScalarTimingCheckConditionUnary { nodes: (a, b) }),
+    ))
+}
+
+#[parser]
+pub fn scalar_timing_check_condition_binary(s: Span) -> IResult<Span, ScalarTimingCheckCondition> {
+    let (s, a) = expression(s)?;
+    let (s, b) = alt((symbol("==="), symbol("=="), symbol("!=="), symbol("!=")))(s)?;
+    let (s, c) = scalar_constant(s)?;
+    Ok((
+        s,
+        ScalarTimingCheckCondition::Binary(ScalarTimingCheckConditionBinary { nodes: (a, b, c) }),
+    ))
+}
+
+#[parser]
+pub fn scalar_constant(s: Span) -> IResult<Span, ScalarConstant> {
+    alt((
+        map(symbol("1'b0"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("1'b1"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("1'B0"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("1'B1"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("'b0"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("'b1"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("'B0"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("'B1"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("1"), |x| ScalarConstant { nodes: (x,) }),
+        map(symbol("0"), |x| ScalarConstant { nodes: (x,) }),
+    ))(s)
+}
diff --git a/src/parser/udp_declaration_and_instantiation/mod.rs b/src/parser/udp_declaration_and_instantiation/mod.rs
index a55f775..8082bcf 100644
--- a/src/parser/udp_declaration_and_instantiation/mod.rs
+++ b/src/parser/udp_declaration_and_instantiation/mod.rs
@@ -1,4 +1,8 @@
+pub mod udp_body;
 pub mod udp_declaration;
 pub mod udp_instantiation;
+pub mod udp_ports;
+pub use udp_body::*;
 pub use udp_declaration::*;
 pub use udp_instantiation::*;
+pub use udp_ports::*;
diff --git a/src/parser/udp_declaration_and_instantiation/udp_body.rs b/src/parser/udp_declaration_and_instantiation/udp_body.rs
new file mode 100644
index 0000000..4b8ca92
--- /dev/null
+++ b/src/parser/udp_declaration_and_instantiation/udp_body.rs
@@ -0,0 +1,315 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::multi::*;
+use nom::sequence::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub enum UdpBody<'a> {
+    CombinationalBody(CombinationalBody<'a>),
+    SequentialBody(SequentialBody<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct CombinationalBody<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        CombinationalEntry<'a>,
+        Vec<CombinationalEntry<'a>>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct CombinationalEntry<'a> {
+    pub nodes: (LevelInputList<'a>, Symbol<'a>, OutputSymbol<'a>, Symbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct SequentialBody<'a> {
+    pub nodes: (
+        Option<UdpInitialStatement<'a>>,
+        Symbol<'a>,
+        SequentialEntry<'a>,
+        Vec<SequentialEntry<'a>>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpInitialStatement<'a> {
+    pub nodes: (
+        Symbol<'a>,
+        OutputPortIdentifier<'a>,
+        Symbol<'a>,
+        InitVal<'a>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct InitVal<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct SequentialEntry<'a> {
+    pub nodes: (
+        SeqInputList<'a>,
+        Symbol<'a>,
+        CurrentState<'a>,
+        Symbol<'a>,
+        NextState<'a>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum SeqInputList<'a> {
+    LevelInputList(LevelInputList<'a>),
+    EdgeInputList(EdgeInputList<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct LevelInputList<'a> {
+    pub nodes: (LevelSymbol<'a>, Vec<LevelSymbol<'a>>),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeInputList<'a> {
+    pub nodes: (
+        Vec<LevelSymbol<'a>>,
+        EdgeIndicator<'a>,
+        Vec<LevelSymbol<'a>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum EdgeIndicator<'a> {
+    Paren(EdgeIndicatorParen<'a>),
+    EdgeSymbol(EdgeSymbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeIndicatorParen<'a> {
+    pub nodes: (Paren<'a, (LevelSymbol<'a>, LevelSymbol<'a>)>,),
+}
+
+#[derive(Debug, Node)]
+pub struct CurrentState<'a> {
+    pub nodes: (LevelSymbol<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub enum NextState<'a> {
+    OutputSymbol(OutputSymbol<'a>),
+    Minus(Symbol<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct OutputSymbol<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct LevelSymbol<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+#[derive(Debug, Node)]
+pub struct EdgeSymbol<'a> {
+    pub nodes: (Symbol<'a>,),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn udp_body(s: Span) -> IResult<Span, UdpBody> {
+    alt((
+        map(combinational_body, |x| UdpBody::CombinationalBody(x)),
+        map(sequential_body, |x| UdpBody::SequentialBody(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn combinational_body(s: Span) -> IResult<Span, CombinationalBody> {
+    let (s, a) = symbol("table")(s)?;
+    let (s, b) = combinational_entry(s)?;
+    let (s, c) = many0(combinational_entry)(s)?;
+    let (s, d) = symbol("endtable")(s)?;
+    Ok((
+        s,
+        CombinationalBody {
+            nodes: (a, b, c, d),
+        },
+    ))
+}
+
+#[parser]
+pub fn combinational_entry(s: Span) -> IResult<Span, CombinationalEntry> {
+    let (s, a) = level_input_list(s)?;
+    let (s, b) = symbol(":")(s)?;
+    let (s, c) = output_symbol(s)?;
+    let (s, d) = symbol(";")(s)?;
+    Ok((
+        s,
+        CombinationalEntry {
+            nodes: (a, b, c, d),
+        },
+    ))
+}
+
+#[parser]
+pub fn sequential_body(s: Span) -> IResult<Span, SequentialBody> {
+    let (s, a) = opt(udp_initial_statement)(s)?;
+    let (s, b) = symbol("table")(s)?;
+    let (s, c) = sequential_entry(s)?;
+    let (s, d) = many0(sequential_entry)(s)?;
+    let (s, e) = symbol("endtable")(s)?;
+    Ok((
+        s,
+        SequentialBody {
+            nodes: (a, b, c, d, e),
+        },
+    ))
+}
+
+#[parser]
+pub fn udp_initial_statement(s: Span) -> IResult<Span, UdpInitialStatement> {
+    let (s, a) = symbol("initial")(s)?;
+    let (s, b) = output_port_identifier(s)?;
+    let (s, c) = symbol("=")(s)?;
+    let (s, d) = init_val(s)?;
+    let (s, e) = symbol(";")(s)?;
+    Ok((
+        s,
+        UdpInitialStatement {
+            nodes: (a, b, c, d, e),
+        },
+    ))
+}
+
+#[parser]
+pub fn init_val(s: Span) -> IResult<Span, InitVal> {
+    alt((
+        map(symbol("1'b0"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'b1"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'bx"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'bX"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'B0"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'B1"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'Bx"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1'BX"), |x| InitVal { nodes: (x,) }),
+        map(symbol("1"), |x| InitVal { nodes: (x,) }),
+        map(symbol("0"), |x| InitVal { nodes: (x,) }),
+    ))(s)
+}
+
+#[parser]
+pub fn sequential_entry(s: Span) -> IResult<Span, SequentialEntry> {
+    let (s, a) = seq_input_list(s)?;
+    let (s, b) = symbol(":")(s)?;
+    let (s, c) = current_state(s)?;
+    let (s, d) = symbol(":")(s)?;
+    let (s, e) = next_state(s)?;
+    let (s, f) = symbol(";")(s)?;
+    Ok((
+        s,
+        SequentialEntry {
+            nodes: (a, b, c, d, e, f),
+        },
+    ))
+}
+
+#[parser]
+pub fn seq_input_list(s: Span) -> IResult<Span, SeqInputList> {
+    alt((
+        map(level_input_list, |x| SeqInputList::LevelInputList(x)),
+        map(edge_input_list, |x| SeqInputList::EdgeInputList(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn level_input_list(s: Span) -> IResult<Span, LevelInputList> {
+    let (s, a) = level_symbol(s)?;
+    let (s, b) = many0(level_symbol)(s)?;
+    Ok((s, LevelInputList { nodes: (a, b) }))
+}
+
+#[parser]
+pub fn edge_input_list(s: Span) -> IResult<Span, EdgeInputList> {
+    let (s, a) = many0(level_symbol)(s)?;
+    let (s, b) = edge_indicator(s)?;
+    let (s, c) = many0(level_symbol)(s)?;
+    Ok((s, EdgeInputList { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn edge_indicator(s: Span) -> IResult<Span, EdgeIndicator> {
+    alt((
+        edge_indicator_paren,
+        map(edge_symbol, |x| EdgeIndicator::EdgeSymbol(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn edge_indicator_paren(s: Span) -> IResult<Span, EdgeIndicator> {
+    let (s, a) = paren(pair(level_symbol, level_symbol))(s)?;
+    Ok((s, EdgeIndicator::Paren(EdgeIndicatorParen { nodes: (a,) })))
+}
+
+#[parser]
+pub fn current_state(s: Span) -> IResult<Span, CurrentState> {
+    let (s, a) = level_symbol(s)?;
+    Ok((s, CurrentState { nodes: (a,) }))
+}
+
+#[parser]
+pub fn next_state(s: Span) -> IResult<Span, NextState> {
+    alt((
+        map(output_symbol, |x| NextState::OutputSymbol(x)),
+        map(symbol("-"), |x| NextState::Minus(x)),
+    ))(s)
+}
+
+#[parser]
+pub fn output_symbol(s: Span) -> IResult<Span, OutputSymbol> {
+    alt((
+        map(symbol("0"), |x| OutputSymbol { nodes: (x,) }),
+        map(symbol("1"), |x| OutputSymbol { nodes: (x,) }),
+        map(symbol("x"), |x| OutputSymbol { nodes: (x,) }),
+        map(symbol("X"), |x| OutputSymbol { nodes: (x,) }),
+    ))(s)
+}
+
+#[parser]
+pub fn level_symbol(s: Span) -> IResult<Span, LevelSymbol> {
+    alt((
+        map(symbol("0"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("1"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("x"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("X"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("?"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("b"), |x| LevelSymbol { nodes: (x,) }),
+        map(symbol("B"), |x| LevelSymbol { nodes: (x,) }),
+    ))(s)
+}
+
+#[parser]
+pub fn edge_symbol(s: Span) -> IResult<Span, EdgeSymbol> {
+    alt((
+        map(symbol("r"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("R"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("f"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("F"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("p"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("P"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("n"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("N"), |x| EdgeSymbol { nodes: (x,) }),
+        map(symbol("*"), |x| EdgeSymbol { nodes: (x,) }),
+    ))(s)
+}
diff --git a/src/parser/udp_declaration_and_instantiation/udp_declaration.rs b/src/parser/udp_declaration_and_instantiation/udp_declaration.rs
index ed4ee9c..f3956bb 100644
--- a/src/parser/udp_declaration_and_instantiation/udp_declaration.rs
+++ b/src/parser/udp_declaration_and_instantiation/udp_declaration.rs
@@ -1,20 +1,199 @@
 use crate::ast::*;
 use crate::parser::*;
-//use nom::branch::*;
-//use nom::combinator::*;
-use nom::error::*;
-use nom::{Err, IResult};
+use nom::branch::*;
+use nom::combinator::*;
+use nom::multi::*;
+use nom::sequence::*;
+use nom::IResult;
 
 // -----------------------------------------------------------------------------
 
 #[derive(Debug, Node)]
-pub struct UdpDeclaration<'a> {
-    pub nodes: (Identifier<'a>,),
+pub struct UdpNonansiDeclaration<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        UdpIdentifier<'a>,
+        Paren<'a, UdpPortList<'a>>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpAnsiDeclaration<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        UdpIdentifier<'a>,
+        Paren<'a, UdpDeclarationPortList<'a>>,
+        Symbol<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum UdpDeclaration<'a> {
+    Nonansi(UdpDeclarationNonansi<'a>),
+    Ansi(UdpDeclarationAnsi<'a>),
+    ExternNonansi(UdpDeclarationExternNonansi<'a>),
+    ExternAnsi(UdpDeclarationExternAnsi<'a>),
+    Wildcard(UdpDeclarationWildcard<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationNonansi<'a> {
+    pub nodes: (
+        UdpNonansiDeclaration<'a>,
+        UdpPortDeclaration<'a>,
+        Vec<UdpPortDeclaration<'a>>,
+        UdpBody<'a>,
+        Symbol<'a>,
+        Option<(Symbol<'a>, UdpIdentifier<'a>)>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationAnsi<'a> {
+    pub nodes: (
+        UdpAnsiDeclaration<'a>,
+        UdpBody<'a>,
+        Symbol<'a>,
+        Option<(Symbol<'a>, UdpIdentifier<'a>)>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationExternNonansi<'a> {
+    pub nodes: (Symbol<'a>, UdpNonansiDeclaration<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationExternAnsi<'a> {
+    pub nodes: (Symbol<'a>, UdpAnsiDeclaration<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationWildcard<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        UdpIdentifier<'a>,
+        Paren<'a, Symbol<'a>>,
+        Symbol<'a>,
+        Vec<UdpPortDeclaration<'a>>,
+        UdpBody<'a>,
+        Symbol<'a>,
+        Option<(Symbol<'a>, UdpIdentifier<'a>)>,
+    ),
 }
 
 // -----------------------------------------------------------------------------
 
 #[parser]
-pub fn udp_declaration(s: Span) -> IResult<Span, UdpDeclaration> {
-    Err(Err::Error(make_error(s, ErrorKind::Fix)))
+pub fn udp_nonansi_declaration(s: Span) -> IResult<Span, UdpNonansiDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("primitive")(s)?;
+    let (s, c) = udp_identifier(s)?;
+    let (s, d) = paren(udp_port_list)(s)?;
+    let (s, e) = symbol(";")(s)?;
+    Ok((
+        s,
+        UdpNonansiDeclaration {
+            nodes: (a, b, c, d, e),
+        },
+    ))
+}
+
+#[parser]
+pub fn udp_ansi_declaration(s: Span) -> IResult<Span, UdpAnsiDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("primitive")(s)?;
+    let (s, c) = udp_identifier(s)?;
+    let (s, d) = paren(udp_declaration_port_list)(s)?;
+    let (s, e) = symbol(";")(s)?;
+    Ok((
+        s,
+        UdpAnsiDeclaration {
+            nodes: (a, b, c, d, e),
+        },
+    ))
+}
+
+#[parser]
+pub fn udp_declaration(s: Span) -> IResult<Span, UdpDeclaration> {
+    alt((
+        udp_declaration_nonansi,
+        udp_declaration_ansi,
+        udp_declaration_extern_nonansi,
+        udp_declaration_extern_ansi,
+        udp_declaration_wildcard,
+    ))(s)
+}
+
+#[parser]
+pub fn udp_declaration_nonansi(s: Span) -> IResult<Span, UdpDeclaration> {
+    let (s, a) = udp_nonansi_declaration(s)?;
+    let (s, b) = udp_port_declaration(s)?;
+    let (s, c) = many0(udp_port_declaration)(s)?;
+    let (s, d) = udp_body(s)?;
+    let (s, e) = symbol("endprimitive")(s)?;
+    let (s, f) = opt(pair(symbol(":"), udp_identifier))(s)?;
+    Ok((
+        s,
+        UdpDeclaration::Nonansi(UdpDeclarationNonansi {
+            nodes: (a, b, c, d, e, f),
+        }),
+    ))
+}
+
+#[parser]
+pub fn udp_declaration_ansi(s: Span) -> IResult<Span, UdpDeclaration> {
+    let (s, a) = udp_ansi_declaration(s)?;
+    let (s, b) = udp_body(s)?;
+    let (s, c) = symbol("endprimitive")(s)?;
+    let (s, d) = opt(pair(symbol(":"), udp_identifier))(s)?;
+    Ok((
+        s,
+        UdpDeclaration::Ansi(UdpDeclarationAnsi {
+            nodes: (a, b, c, d),
+        }),
+    ))
+}
+
+#[parser]
+pub fn udp_declaration_extern_nonansi(s: Span) -> IResult<Span, UdpDeclaration> {
+    let (s, a) = symbol("extern")(s)?;
+    let (s, b) = udp_nonansi_declaration(s)?;
+    Ok((
+        s,
+        UdpDeclaration::ExternNonansi(UdpDeclarationExternNonansi { nodes: (a, b) }),
+    ))
+}
+
+#[parser]
+pub fn udp_declaration_extern_ansi(s: Span) -> IResult<Span, UdpDeclaration> {
+    let (s, a) = symbol("extern")(s)?;
+    let (s, b) = udp_ansi_declaration(s)?;
+    Ok((
+        s,
+        UdpDeclaration::ExternAnsi(UdpDeclarationExternAnsi { nodes: (a, b) }),
+    ))
+}
+
+#[parser]
+pub fn udp_declaration_wildcard(s: Span) -> IResult<Span, UdpDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("primitive")(s)?;
+    let (s, c) = udp_identifier(s)?;
+    let (s, d) = paren(symbol(".*"))(s)?;
+    let (s, e) = symbol(";")(s)?;
+    let (s, f) = many0(udp_port_declaration)(s)?;
+    let (s, g) = udp_body(s)?;
+    let (s, h) = symbol("endprimitive")(s)?;
+    let (s, i) = opt(pair(symbol(":"), udp_identifier))(s)?;
+    Ok((
+        s,
+        UdpDeclaration::Wildcard(UdpDeclarationWildcard {
+            nodes: (a, b, c, d, e, f, g, h, i),
+        }),
+    ))
 }
diff --git a/src/parser/udp_declaration_and_instantiation/udp_ports.rs b/src/parser/udp_declaration_and_instantiation/udp_ports.rs
new file mode 100644
index 0000000..ad11bd9
--- /dev/null
+++ b/src/parser/udp_declaration_and_instantiation/udp_ports.rs
@@ -0,0 +1,154 @@
+use crate::ast::*;
+use crate::parser::*;
+use nom::branch::*;
+use nom::combinator::*;
+use nom::multi::*;
+use nom::sequence::*;
+use nom::IResult;
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug, Node)]
+pub struct UdpPortList<'a> {
+    pub nodes: (
+        OutputPortIdentifier<'a>,
+        Symbol<'a>,
+        List<Symbol<'a>, InputPortIdentifier<'a>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpDeclarationPortList<'a> {
+    pub nodes: (
+        UdpOutputDeclaration<'a>,
+        Symbol<'a>,
+        List<Symbol<'a>, UdpInputDeclaration<'a>>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub enum UdpPortDeclaration<'a> {
+    UdpOutputDeclaration((UdpOutputDeclaration<'a>, Symbol<'a>)),
+    UdpInputDeclaration((UdpInputDeclaration<'a>, Symbol<'a>)),
+    UdpRegDeclaration((UdpRegDeclaration<'a>, Symbol<'a>)),
+}
+
+#[derive(Debug, Node)]
+pub enum UdpOutputDeclaration<'a> {
+    Nonreg(UdpOutputDeclarationNonreg<'a>),
+    Reg(UdpOutputDeclarationReg<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpOutputDeclarationNonreg<'a> {
+    pub nodes: (Vec<AttributeInstance<'a>>, Symbol<'a>, PortIdentifier<'a>),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpOutputDeclarationReg<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        Symbol<'a>,
+        PortIdentifier<'a>,
+        Option<(Symbol<'a>, ConstantExpression<'a>)>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpInputDeclaration<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        ListOfUdpPortIdentifiers<'a>,
+    ),
+}
+
+#[derive(Debug, Node)]
+pub struct UdpRegDeclaration<'a> {
+    pub nodes: (
+        Vec<AttributeInstance<'a>>,
+        Symbol<'a>,
+        VariableIdentifier<'a>,
+    ),
+}
+
+// -----------------------------------------------------------------------------
+
+#[parser]
+pub fn udp_port_list(s: Span) -> IResult<Span, UdpPortList> {
+    let (s, a) = output_port_identifier(s)?;
+    let (s, b) = symbol(",")(s)?;
+    let (s, c) = list(symbol(","), input_port_identifier)(s)?;
+    Ok((s, UdpPortList { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn udp_declaration_port_list(s: Span) -> IResult<Span, UdpDeclarationPortList> {
+    let (s, a) = udp_output_declaration(s)?;
+    let (s, b) = symbol(",")(s)?;
+    let (s, c) = list(symbol(","), udp_input_declaration)(s)?;
+    Ok((s, UdpDeclarationPortList { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn udp_port_declaration(s: Span) -> IResult<Span, UdpPortDeclaration> {
+    alt((
+        map(pair(udp_output_declaration, symbol(";")), |x| {
+            UdpPortDeclaration::UdpOutputDeclaration(x)
+        }),
+        map(pair(udp_input_declaration, symbol(";")), |x| {
+            UdpPortDeclaration::UdpInputDeclaration(x)
+        }),
+        map(pair(udp_reg_declaration, symbol(";")), |x| {
+            UdpPortDeclaration::UdpRegDeclaration(x)
+        }),
+    ))(s)
+}
+
+#[parser]
+pub fn udp_output_declaration(s: Span) -> IResult<Span, UdpOutputDeclaration> {
+    alt((udp_output_declaration_nonreg, udp_output_declaration_reg))(s)
+}
+
+#[parser]
+pub fn udp_output_declaration_nonreg(s: Span) -> IResult<Span, UdpOutputDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("output")(s)?;
+    let (s, c) = port_identifier(s)?;
+    Ok((
+        s,
+        UdpOutputDeclaration::Nonreg(UdpOutputDeclarationNonreg { nodes: (a, b, c) }),
+    ))
+}
+
+#[parser]
+pub fn udp_output_declaration_reg(s: Span) -> IResult<Span, UdpOutputDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("output")(s)?;
+    let (s, c) = symbol("reg")(s)?;
+    let (s, d) = port_identifier(s)?;
+    let (s, e) = opt(pair(symbol("="), constant_expression))(s)?;
+    Ok((
+        s,
+        UdpOutputDeclaration::Reg(UdpOutputDeclarationReg {
+            nodes: (a, b, c, d, e),
+        }),
+    ))
+}
+
+#[parser]
+pub fn udp_input_declaration(s: Span) -> IResult<Span, UdpInputDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("input")(s)?;
+    let (s, c) = list_of_udp_port_identifiers(s)?;
+    Ok((s, UdpInputDeclaration { nodes: (a, b, c) }))
+}
+
+#[parser]
+pub fn udp_reg_declaration(s: Span) -> IResult<Span, UdpRegDeclaration> {
+    let (s, a) = many0(attribute_instance)(s)?;
+    let (s, b) = symbol("reg")(s)?;
+    let (s, c) = variable_identifier(s)?;
+    Ok((s, UdpRegDeclaration { nodes: (a, b, c) }))
+}