diff --git a/sv-parser-parser/Cargo.toml b/sv-parser-parser/Cargo.toml
index 00a0d49..2464b2d 100644
--- a/sv-parser-parser/Cargo.toml
+++ b/sv-parser-parser/Cargo.toml
@@ -11,7 +11,6 @@ trace   = ["nom-tracable/trace"]
 [dependencies]
 nom                  = "5.0.0"
 nom_locate           = "0.4.0"
-nom-both             = {path = "../../nom-both/nom-both"}
 nom-packrat          = {path = "../../nom-packrat/nom-packrat"}
 nom-recursive        = {path = "../../nom-recursive/nom-recursive"}
 nom-tracable         = {path = "../../nom-tracable/nom-tracable"}
diff --git a/sv-parser-parser/src/declarations/assertion_declarations.rs b/sv-parser-parser/src/declarations/assertion_declarations.rs
index e91968b..817c45a 100644
--- a/sv-parser-parser/src/declarations/assertion_declarations.rs
+++ b/sv-parser-parser/src/declarations/assertion_declarations.rs
@@ -234,12 +234,11 @@ pub(crate) fn property_port_list(s: Span) -> IResult<Span, PropertyPortList> {
     Ok((s, PropertyPortList { nodes: (a,) }))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn property_port_item(s: Span) -> IResult<Span, PropertyPortItem> {
     let (s, a) = many0(attribute_instance)(s)?;
     let (s, b) = opt(pair(local, opt(property_lvar_port_direction)))(s)?;
-    let (s, c) = both_opt(property_formal_type)(s)?;
+    let (s, c) = property_formal_type(s)?;
     let (s, d) = formal_port_identifier(s)?;
     let (s, e) = many0(variable_dimension)(s)?;
     let (s, f) = opt(pair(symbol("="), property_actual_arg))(s)?;
@@ -724,12 +723,11 @@ pub(crate) fn sequence_port_list(s: Span) -> IResult<Span, SequencePortList> {
     Ok((s, SequencePortList { nodes: (a,) }))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn sequence_port_item(s: Span) -> IResult<Span, SequencePortItem> {
     let (s, a) = many0(attribute_instance)(s)?;
     let (s, b) = opt(pair(local, opt(sequence_lvar_port_direction)))(s)?;
-    let (s, c) = both_opt(sequence_formal_type)(s)?;
+    let (s, c) = sequence_formal_type(s)?;
     let (s, d) = formal_port_identifier(s)?;
     let (s, e) = many0(variable_dimension)(s)?;
     let (s, f) = opt(pair(symbol("="), sequence_actual_arg))(s)?;
@@ -759,7 +757,7 @@ pub(crate) fn sequence_lvar_port_direction(s: Span) -> IResult<Span, SequenceLva
 #[tracable_parser]
 pub(crate) fn sequence_formal_type(s: Span) -> IResult<Span, SequenceFormalType> {
     alt((
-        map(data_type_or_implicit, |x| {
+        map(data_type_or_implicit_sequence_formal_type, |x| {
             SequenceFormalType::DataTypeOrImplicit(Box::new(x))
         }),
         map(keyword("sequence"), |x| {
@@ -771,6 +769,21 @@ pub(crate) fn sequence_formal_type(s: Span) -> IResult<Span, SequenceFormalType>
     ))(s)
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_sequence_formal_type(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(formal_port_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(formal_port_identifier)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn sequence_expr(s: Span) -> IResult<Span, SequenceExpr> {
     alt((
diff --git a/sv-parser-parser/src/declarations/covergroup_declarations.rs b/sv-parser-parser/src/declarations/covergroup_declarations.rs
index 5437f2e..06a8b33 100644
--- a/sv-parser-parser/src/declarations/covergroup_declarations.rs
+++ b/sv-parser-parser/src/declarations/covergroup_declarations.rs
@@ -206,11 +206,10 @@ pub(crate) fn hierarchical_identifier_or_class_scope(
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn cover_point(s: Span) -> IResult<Span, CoverPoint> {
     let (s, a) = opt(triple(
-        both_opt(data_type_or_implicit),
+        opt(data_type_or_implicit_cover_point),
         cover_point_identifier,
         symbol(":"),
     ))(s)?;
@@ -226,6 +225,19 @@ pub(crate) fn cover_point(s: Span) -> IResult<Span, CoverPoint> {
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_cover_point(s: Span) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(cover_point_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(cover_point_identifier)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn bins_or_empty(s: Span) -> IResult<Span, BinsOrEmpty> {
     alt((
diff --git a/sv-parser-parser/src/declarations/function_declarations.rs b/sv-parser-parser/src/declarations/function_declarations.rs
index 559b6ac..ae10efd 100644
--- a/sv-parser-parser/src/declarations/function_declarations.rs
+++ b/sv-parser-parser/src/declarations/function_declarations.rs
@@ -5,12 +5,26 @@ use crate::*;
 #[tracable_parser]
 pub(crate) fn function_data_type_or_implicit(s: Span) -> IResult<Span, FunctionDataTypeOrImplicit> {
     alt((
-        map(data_type_or_void, |x| {
-            FunctionDataTypeOrImplicit::DataTypeOrVoid(Box::new(x))
-        }),
-        map(implicit_data_type, |x| {
-            FunctionDataTypeOrImplicit::ImplicitDataType(Box::new(x))
-        }),
+        map(
+            terminated(
+                data_type_or_void,
+                peek(pair(
+                    opt(interface_identifier_or_class_scope),
+                    function_identifier,
+                )),
+            ),
+            |x| FunctionDataTypeOrImplicit::DataTypeOrVoid(Box::new(x)),
+        ),
+        map(
+            terminated(
+                implicit_data_type,
+                peek(pair(
+                    opt(interface_identifier_or_class_scope),
+                    function_identifier,
+                )),
+            ),
+            |x| FunctionDataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
     ))(s)
 }
 
@@ -30,12 +44,11 @@ pub(crate) fn function_body_declaration(s: Span) -> IResult<Span, FunctionBodyDe
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn function_body_declaration_without_port(
     s: Span,
 ) -> IResult<Span, FunctionBodyDeclaration> {
-    let (s, a) = both_opt(function_data_type_or_implicit)(s)?;
+    let (s, a) = function_data_type_or_implicit(s)?;
     let (s, b) = opt(interface_identifier_or_class_scope)(s)?;
     let (s, c) = function_identifier(s)?;
     let (s, d) = symbol(";")(s)?;
@@ -51,12 +64,11 @@ pub(crate) fn function_body_declaration_without_port(
     ))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn function_body_declaration_with_port(
     s: Span,
 ) -> IResult<Span, FunctionBodyDeclaration> {
-    let (s, a) = both_opt(function_data_type_or_implicit)(s)?;
+    let (s, a) = function_data_type_or_implicit(s)?;
     let (s, b) = opt(interface_identifier_or_class_scope)(s)?;
     let (s, c) = function_identifier(s)?;
     let (s, d) = paren(opt(tf_port_list))(s)?;
diff --git a/sv-parser-parser/src/declarations/let_declarations.rs b/sv-parser-parser/src/declarations/let_declarations.rs
index 13c854e..5d74627 100644
--- a/sv-parser-parser/src/declarations/let_declarations.rs
+++ b/sv-parser-parser/src/declarations/let_declarations.rs
@@ -30,11 +30,10 @@ pub(crate) fn let_port_list(s: Span) -> IResult<Span, LetPortList> {
     Ok((s, LetPortList { nodes: (a,) }))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn let_port_item(s: Span) -> IResult<Span, LetPortItem> {
     let (s, a) = many0(attribute_instance)(s)?;
-    let (s, b) = both_opt(let_formal_type)(s)?;
+    let (s, b) = let_formal_type(s)?;
     let (s, c) = formal_port_identifier(s)?;
     let (s, d) = many0(variable_dimension)(s)?;
     let (s, e) = opt(pair(symbol("="), expression))(s)?;
@@ -49,13 +48,26 @@ pub(crate) fn let_port_item(s: Span) -> IResult<Span, LetPortItem> {
 #[tracable_parser]
 pub(crate) fn let_formal_type(s: Span) -> IResult<Span, LetFormalType> {
     alt((
-        map(data_type_or_implicit, |x| {
+        map(data_type_or_implicit_let_formal_type, |x| {
             LetFormalType::DataTypeOrImplicit(Box::new(x))
         }),
         map(keyword("untyped"), |x| LetFormalType::Untyped(Box::new(x))),
     ))(s)
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_let_formal_type(s: Span) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(formal_port_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(formal_port_identifier)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn let_expression(s: Span) -> IResult<Span, LetExpression> {
     let (s, a) = opt(package_scope)(s)?;
diff --git a/sv-parser-parser/src/declarations/module_parameter_declarations.rs b/sv-parser-parser/src/declarations/module_parameter_declarations.rs
index 38a699d..cfaecfe 100644
--- a/sv-parser-parser/src/declarations/module_parameter_declarations.rs
+++ b/sv-parser-parser/src/declarations/module_parameter_declarations.rs
@@ -10,13 +10,12 @@ pub(crate) fn local_parameter_declaration(s: Span) -> IResult<Span, LocalParamet
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn local_parameter_declaration_param(
     s: Span,
 ) -> IResult<Span, LocalParameterDeclaration> {
     let (s, a) = keyword("localparam")(s)?;
-    let (s, b) = both_opt(data_type_or_implicit)(s)?;
+    let (s, b) = data_type_or_implicit_local_parameter_declaration_param(s)?;
     let (s, c) = list_of_param_assignments(s)?;
     Ok((
         s,
@@ -26,6 +25,21 @@ pub(crate) fn local_parameter_declaration_param(
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_local_parameter_declaration_param(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(param_assignment)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(param_assignment)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn local_parameter_declaration_type(
     s: Span,
@@ -46,11 +60,10 @@ pub(crate) fn parameter_declaration(s: Span) -> IResult<Span, ParameterDeclarati
     alt((parameter_declaration_param, parameter_declaration_type))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn parameter_declaration_param(s: Span) -> IResult<Span, ParameterDeclaration> {
     let (s, a) = keyword("parameter")(s)?;
-    let (s, b) = both_opt(data_type_or_implicit)(s)?;
+    let (s, b) = data_type_or_implicit_parameter_declaration_param(s)?;
     let (s, c) = list_of_param_assignments(s)?;
     Ok((
         s,
@@ -58,6 +71,21 @@ pub(crate) fn parameter_declaration_param(s: Span) -> IResult<Span, ParameterDec
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_parameter_declaration_param(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(param_assignment)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(param_assignment)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn parameter_declaration_type(s: Span) -> IResult<Span, ParameterDeclaration> {
     let (s, a) = keyword("parameter")(s)?;
diff --git a/sv-parser-parser/src/declarations/net_and_variable_types.rs b/sv-parser-parser/src/declarations/net_and_variable_types.rs
index d33d7fb..d0d9911 100644
--- a/sv-parser-parser/src/declarations/net_and_variable_types.rs
+++ b/sv-parser-parser/src/declarations/net_and_variable_types.rs
@@ -121,6 +121,8 @@ pub(crate) fn data_type_type(s: Span) -> IResult<Span, DataType> {
     ))
 }
 
+// all data_type_or_implicit call are specialized for each parser
+#[allow(dead_code)]
 #[tracable_parser]
 pub(crate) fn data_type_or_implicit(s: Span) -> IResult<Span, DataTypeOrImplicit> {
     alt((
@@ -293,13 +295,27 @@ pub(crate) fn net_port_type(s: Span) -> IResult<Span, NetPortType> {
 #[tracable_parser]
 pub(crate) fn net_port_type_data_type(s: Span) -> IResult<Span, NetPortType> {
     let (s, a) = opt(net_type)(s)?;
-    let (s, b) = data_type_or_implicit(s)?;
+    let (s, b) = data_type_or_implicit_net_port_type_data_type(s)?;
     Ok((
         s,
         NetPortType::DataType(Box::new(NetPortTypeDataType { nodes: (a, b) })),
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_net_port_type_data_type(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(port_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(terminated(implicit_data_type, peek(port_identifier)), |x| {
+            DataTypeOrImplicit::ImplicitDataType(Box::new(x))
+        }),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn net_port_type_interconnect(s: Span) -> IResult<Span, NetPortType> {
     let (s, a) = keyword("interconnect")(s)?;
@@ -319,7 +335,9 @@ pub(crate) fn variable_port_type(s: Span) -> IResult<Span, VariablePortType> {
 #[tracable_parser]
 pub(crate) fn var_data_type(s: Span) -> IResult<Span, VarDataType> {
     alt((
-        map(data_type, |x| VarDataType::DataType(Box::new(x))),
+        map(terminated(data_type, peek(variable_identifier)), |x| {
+            VarDataType::DataType(Box::new(x))
+        }),
         var_data_type_var,
     ))(s)
 }
@@ -327,13 +345,28 @@ pub(crate) fn var_data_type(s: Span) -> IResult<Span, VarDataType> {
 #[tracable_parser]
 pub(crate) fn var_data_type_var(s: Span) -> IResult<Span, VarDataType> {
     let (s, a) = keyword("var")(s)?;
-    let (s, b) = data_type_or_implicit(s)?;
+    let (s, b) = data_type_or_implicit_var_data_type_var(s)?;
     Ok((
         s,
         VarDataType::Var(Box::new(VarDataTypeVar { nodes: (a, b) })),
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_var_data_type_var(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(variable_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(variable_identifier)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn signing(s: Span) -> IResult<Span, Signing> {
     alt((
diff --git a/sv-parser-parser/src/declarations/port_declarations.rs b/sv-parser-parser/src/declarations/port_declarations.rs
index d2baa6f..011d0e4 100644
--- a/sv-parser-parser/src/declarations/port_declarations.rs
+++ b/sv-parser-parser/src/declarations/port_declarations.rs
@@ -2,11 +2,10 @@ use crate::*;
 
 // -----------------------------------------------------------------------------
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn inout_declaration(s: Span) -> IResult<Span, InoutDeclaration> {
     let (s, a) = keyword("inout")(s)?;
-    let (s, b) = both_opt(net_port_type)(s)?;
+    let (s, b) = net_port_type(s)?;
     let (s, c) = list_of_port_identifiers(s)?;
     Ok((s, InoutDeclaration { nodes: (a, b, c) }))
 }
@@ -16,11 +15,10 @@ pub(crate) fn input_declaration(s: Span) -> IResult<Span, InputDeclaration> {
     alt((input_declaration_net, input_declaration_variable))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn input_declaration_net(s: Span) -> IResult<Span, InputDeclaration> {
     let (s, a) = keyword("input")(s)?;
-    let (s, b) = both_opt(net_port_type)(s)?;
+    let (s, b) = net_port_type(s)?;
     let (s, c) = list_of_port_identifiers(s)?;
     Ok((
         s,
@@ -28,11 +26,10 @@ pub(crate) fn input_declaration_net(s: Span) -> IResult<Span, InputDeclaration>
     ))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn input_declaration_variable(s: Span) -> IResult<Span, InputDeclaration> {
     let (s, a) = keyword("input")(s)?;
-    let (s, b) = both_alt(variable_port_type, implicit_var)(s)?;
+    let (s, b) = variable_port_type(s)?;
     let (s, c) = list_of_variable_identifiers(s)?;
     Ok((
         s,
@@ -45,11 +42,10 @@ pub(crate) fn output_declaration(s: Span) -> IResult<Span, OutputDeclaration> {
     alt((output_declaration_net, output_declaration_variable))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn output_declaration_net(s: Span) -> IResult<Span, OutputDeclaration> {
     let (s, a) = keyword("output")(s)?;
-    let (s, b) = both_opt(net_port_type)(s)?;
+    let (s, b) = net_port_type(s)?;
     let (s, c) = list_of_port_identifiers(s)?;
     Ok((
         s,
@@ -57,11 +53,10 @@ pub(crate) fn output_declaration_net(s: Span) -> IResult<Span, OutputDeclaration
     ))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn output_declaration_variable(s: Span) -> IResult<Span, OutputDeclaration> {
     let (s, a) = keyword("output")(s)?;
-    let (s, b) = both_alt(variable_port_type, implicit_var)(s)?;
+    let (s, b) = variable_port_type(s)?;
     let (s, c) = list_of_variable_port_identifiers(s)?;
     Ok((
         s,
@@ -77,29 +72,10 @@ pub(crate) fn interface_port_declaration(s: Span) -> IResult<Span, InterfacePort
     Ok((s, InterfacePortDeclaration { nodes: (a, b, c) }))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn ref_declaration(s: Span) -> IResult<Span, RefDeclaration> {
     let (s, a) = keyword("ref")(s)?;
-    let (s, b) = both_alt(variable_port_type, implicit_var)(s)?;
+    let (s, b) = variable_port_type(s)?;
     let (s, c) = list_of_variable_identifiers(s)?;
     Ok((s, RefDeclaration { nodes: (a, b, c) }))
 }
-
-#[tracable_parser]
-pub(crate) fn implicit_var(s: Span) -> IResult<Span, VariablePortType> {
-    let (s, a) = keyword("var")(s)?;
-    Ok((
-        s,
-        VariablePortType {
-            nodes: (VarDataType::Var(Box::new(VarDataTypeVar {
-                nodes: (
-                    a,
-                    DataTypeOrImplicit::ImplicitDataType(Box::new(ImplicitDataType {
-                        nodes: (None, vec![]),
-                    })),
-                ),
-            })),),
-        },
-    ))
-}
diff --git a/sv-parser-parser/src/declarations/task_declarations.rs b/sv-parser-parser/src/declarations/task_declarations.rs
index 5c6798d..1ba48b5 100644
--- a/sv-parser-parser/src/declarations/task_declarations.rs
+++ b/sv-parser-parser/src/declarations/task_declarations.rs
@@ -71,13 +71,12 @@ pub(crate) fn tf_port_list(s: Span) -> IResult<Span, TfPortList> {
     Ok((s, TfPortList { nodes: (a,) }))
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn tf_port_item(s: Span) -> IResult<Span, TfPortItem> {
     let (s, a) = many0(attribute_instance)(s)?;
     let (s, b) = opt(tf_port_direction)(s)?;
     let (s, c) = opt(var)(s)?;
-    let (s, d) = both_opt(data_type_or_implicit)(s)?;
+    let (s, d) = data_type_or_implicit_tf_port_item(s)?;
     let (s, e) = opt(triple(
         port_identifier,
         many0(variable_dimension),
@@ -91,6 +90,40 @@ pub(crate) fn tf_port_item(s: Span) -> IResult<Span, TfPortItem> {
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_tf_port_item(s: Span) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(
+            terminated(
+                data_type,
+                peek(pair(
+                    opt(triple(
+                        port_identifier,
+                        many0(variable_dimension),
+                        opt(pair(symbol(":"), expression)),
+                    )),
+                    alt((symbol(","), symbol(")"))),
+                )),
+            ),
+            |x| DataTypeOrImplicit::DataType(Box::new(x)),
+        ),
+        map(
+            terminated(
+                implicit_data_type,
+                peek(pair(
+                    opt(triple(
+                        port_identifier,
+                        many0(variable_dimension),
+                        opt(pair(symbol(":"), expression)),
+                    )),
+                    alt((symbol(","), symbol(")"))),
+                )),
+            ),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn tf_port_direction(s: Span) -> IResult<Span, TfPortDirection> {
     alt((
@@ -103,13 +136,12 @@ pub(crate) fn tf_port_direction(s: Span) -> IResult<Span, TfPortDirection> {
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn tf_port_declaration(s: Span) -> IResult<Span, TfPortDeclaration> {
     let (s, a) = many0(attribute_instance)(s)?;
     let (s, b) = tf_port_direction(s)?;
     let (s, c) = opt(var)(s)?;
-    let (s, d) = both_opt(data_type_or_implicit)(s)?;
+    let (s, d) = data_type_or_implicit_tf_port_declaration(s)?;
     let (s, e) = list_of_tf_variable_identifiers(s)?;
     let (s, f) = symbol(";")(s)?;
     Ok((
@@ -120,6 +152,21 @@ pub(crate) fn tf_port_declaration(s: Span) -> IResult<Span, TfPortDeclaration> {
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_tf_port_declaration(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(variable_identifier)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(variable_identifier)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn task_prototype(s: Span) -> IResult<Span, TaskPrototype> {
     let (s, a) = keyword("task")(s)?;
diff --git a/sv-parser-parser/src/declarations/type_declarations.rs b/sv-parser-parser/src/declarations/type_declarations.rs
index c188806..ef0ebd7 100644
--- a/sv-parser-parser/src/declarations/type_declarations.rs
+++ b/sv-parser-parser/src/declarations/type_declarations.rs
@@ -18,13 +18,12 @@ pub(crate) fn data_declaration(s: Span) -> IResult<Span, DataDeclaration> {
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn data_declaration_variable(s: Span) -> IResult<Span, DataDeclaration> {
     let (s, a) = opt(r#const)(s)?;
     let (s, b) = opt(var)(s)?;
     let (s, c) = opt(lifetime)(s)?;
-    let (s, d) = both_opt(data_type_or_implicit)(s)?;
+    let (s, d) = data_type_or_implicit_data_declaration_variable(s)?;
     let (s, e) = list_of_variable_decl_assignments(s)?;
     let (s, f) = symbol(";")(s)?;
     Ok((
@@ -35,6 +34,21 @@ pub(crate) fn data_declaration_variable(s: Span) -> IResult<Span, DataDeclaratio
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_data_declaration_variable(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(terminated(data_type, peek(variable_decl_assignment)), |x| {
+            DataTypeOrImplicit::DataType(Box::new(x))
+        }),
+        map(
+            terminated(implicit_data_type, peek(variable_decl_assignment)),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn r#const(s: Span) -> IResult<Span, Const> {
     let (s, a) = keyword("const")(s)?;
@@ -127,13 +141,12 @@ pub(crate) fn net_declaration(s: Span) -> IResult<Span, NetDeclaration> {
     ))(s)
 }
 
-#[both_parser]
 #[tracable_parser]
 pub(crate) fn net_declaration_net_type(s: Span) -> IResult<Span, NetDeclaration> {
     let (s, a) = net_type(s)?;
     let (s, b) = opt(strength)(s)?;
     let (s, c) = opt(vector_scalar)(s)?;
-    let (s, d) = both_opt(data_type_or_implicit)(s)?;
+    let (s, d) = data_type_or_implicit_net_declaration_net_type(s)?;
     let (s, e) = opt(delay3)(s)?;
     let (s, f) = list_of_net_decl_assignments(s)?;
     let (s, g) = symbol(";")(s)?;
@@ -145,6 +158,25 @@ pub(crate) fn net_declaration_net_type(s: Span) -> IResult<Span, NetDeclaration>
     ))
 }
 
+#[tracable_parser]
+pub(crate) fn data_type_or_implicit_net_declaration_net_type(
+    s: Span,
+) -> IResult<Span, DataTypeOrImplicit> {
+    alt((
+        map(
+            terminated(data_type, peek(pair(opt(delay3), net_decl_assignment))),
+            |x| DataTypeOrImplicit::DataType(Box::new(x)),
+        ),
+        map(
+            terminated(
+                implicit_data_type,
+                peek(pair(opt(delay3), net_decl_assignment)),
+            ),
+            |x| DataTypeOrImplicit::ImplicitDataType(Box::new(x)),
+        ),
+    ))(s)
+}
+
 #[tracable_parser]
 pub(crate) fn strength(s: Span) -> IResult<Span, Strength> {
     alt((
diff --git a/sv-parser-parser/src/lib.rs b/sv-parser-parser/src/lib.rs
index 5e4bbcf..72f0790 100644
--- a/sv-parser-parser/src/lib.rs
+++ b/sv-parser-parser/src/lib.rs
@@ -31,7 +31,6 @@ pub(crate) use nom::error::{make_error, ErrorKind};
 pub(crate) use nom::multi::*;
 pub(crate) use nom::sequence::*;
 pub(crate) use nom::{Err, IResult};
-pub(crate) use nom_both::both_parser;
 pub(crate) use nom_packrat::{self, packrat_parser, HasExtraState};
 pub(crate) use nom_recursive::{recursive_parser, HasRecursiveInfo, RecursiveInfo};
 pub(crate) use nom_tracable::tracable_parser;
diff --git a/sv-parser-parser/src/tests.rs b/sv-parser-parser/src/tests.rs
index b1e3f64..a7d571d 100644
--- a/sv-parser-parser/src/tests.rs
+++ b/sv-parser-parser/src/tests.rs
@@ -803,3 +803,18 @@ fn test_attribute_instance() {
 fn test_expression() {
     test!(expression, "(!a ? 0 : !b : 1 : c ? 0 : 1)", Ok((_, _)));
 }
+
+#[test]
+fn test_clause3() {
+    test!(
+        module_declaration,
+        r##"module mux2to1 (input wire a, b, sel, // combined port and type declaration
+                            output logic y);
+              always_comb begin // procedural block
+                if (sel) y = a; // procedural statement
+                else y = b;
+              end
+            endmodule: mux2to1"##,
+        Ok((_, _))
+    );
+}
diff --git a/sv-parser-syntaxtree/src/declarations/assertion_declarations.rs b/sv-parser-syntaxtree/src/declarations/assertion_declarations.rs
index ece821b..1d0440a 100644
--- a/sv-parser-syntaxtree/src/declarations/assertion_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/assertion_declarations.rs
@@ -129,7 +129,7 @@ pub struct PropertyPortItem {
     pub nodes: (
         Vec<AttributeInstance>,
         Option<(Local, Option<PropertyLvarPortDirection>)>,
-        Option<PropertyFormalType>,
+        PropertyFormalType,
         FormalPortIdentifier,
         Vec<VariableDimension>,
         Option<(Symbol, PropertyActualArg)>,
@@ -400,7 +400,7 @@ pub struct SequencePortItem {
     pub nodes: (
         Vec<AttributeInstance>,
         Option<(Local, Option<SequenceLvarPortDirection>)>,
-        Option<SequenceFormalType>,
+        SequenceFormalType,
         FormalPortIdentifier,
         Vec<VariableDimension>,
         Option<(Symbol, SequenceActualArg)>,
diff --git a/sv-parser-syntaxtree/src/declarations/function_declarations.rs b/sv-parser-syntaxtree/src/declarations/function_declarations.rs
index bcda0b2..5e52898 100644
--- a/sv-parser-syntaxtree/src/declarations/function_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/function_declarations.rs
@@ -22,7 +22,7 @@ pub enum FunctionBodyDeclaration {
 #[derive(Clone, Debug, Node)]
 pub struct FunctionBodyDeclarationWithoutPort {
     pub nodes: (
-        Option<FunctionDataTypeOrImplicit>,
+        FunctionDataTypeOrImplicit,
         Option<InterfaceIdentifierOrClassScope>,
         FunctionIdentifier,
         Symbol,
@@ -36,7 +36,7 @@ pub struct FunctionBodyDeclarationWithoutPort {
 #[derive(Clone, Debug, Node)]
 pub struct FunctionBodyDeclarationWithPort {
     pub nodes: (
-        Option<FunctionDataTypeOrImplicit>,
+        FunctionDataTypeOrImplicit,
         Option<InterfaceIdentifierOrClassScope>,
         FunctionIdentifier,
         Paren<Option<TfPortList>>,
diff --git a/sv-parser-syntaxtree/src/declarations/let_declarations.rs b/sv-parser-syntaxtree/src/declarations/let_declarations.rs
index 12d311f..d003961 100644
--- a/sv-parser-syntaxtree/src/declarations/let_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/let_declarations.rs
@@ -28,7 +28,7 @@ pub struct LetPortList {
 pub struct LetPortItem {
     pub nodes: (
         Vec<AttributeInstance>,
-        Option<LetFormalType>,
+        LetFormalType,
         FormalPortIdentifier,
         Vec<VariableDimension>,
         Option<(Symbol, Expression)>,
diff --git a/sv-parser-syntaxtree/src/declarations/module_parameter_declarations.rs b/sv-parser-syntaxtree/src/declarations/module_parameter_declarations.rs
index 013f1ec..9203ff2 100644
--- a/sv-parser-syntaxtree/src/declarations/module_parameter_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/module_parameter_declarations.rs
@@ -10,7 +10,7 @@ pub enum LocalParameterDeclaration {
 
 #[derive(Clone, Debug, Node)]
 pub struct LocalParameterDeclarationParam {
-    pub nodes: (Keyword, Option<DataTypeOrImplicit>, ListOfParamAssignments),
+    pub nodes: (Keyword, DataTypeOrImplicit, ListOfParamAssignments),
 }
 
 #[derive(Clone, Debug, Node)]
@@ -26,7 +26,7 @@ pub enum ParameterDeclaration {
 
 #[derive(Clone, Debug, Node)]
 pub struct ParameterDeclarationParam {
-    pub nodes: (Keyword, Option<DataTypeOrImplicit>, ListOfParamAssignments),
+    pub nodes: (Keyword, DataTypeOrImplicit, ListOfParamAssignments),
 }
 
 #[derive(Clone, Debug, Node)]
diff --git a/sv-parser-syntaxtree/src/declarations/port_declarations.rs b/sv-parser-syntaxtree/src/declarations/port_declarations.rs
index c0f39e7..df8cc6f 100644
--- a/sv-parser-syntaxtree/src/declarations/port_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/port_declarations.rs
@@ -4,7 +4,7 @@ use crate::*;
 
 #[derive(Clone, Debug, Node)]
 pub struct InoutDeclaration {
-    pub nodes: (Keyword, Option<NetPortType>, ListOfPortIdentifiers),
+    pub nodes: (Keyword, NetPortType, ListOfPortIdentifiers),
 }
 
 #[derive(Clone, Debug, Node)]
@@ -15,7 +15,7 @@ pub enum InputDeclaration {
 
 #[derive(Clone, Debug, Node)]
 pub struct InputDeclarationNet {
-    pub nodes: (Keyword, Option<NetPortType>, ListOfPortIdentifiers),
+    pub nodes: (Keyword, NetPortType, ListOfPortIdentifiers),
 }
 
 #[derive(Clone, Debug, Node)]
@@ -31,7 +31,7 @@ pub enum OutputDeclaration {
 
 #[derive(Clone, Debug, Node)]
 pub struct OutputDeclarationNet {
-    pub nodes: (Keyword, Option<NetPortType>, ListOfPortIdentifiers),
+    pub nodes: (Keyword, NetPortType, ListOfPortIdentifiers),
 }
 
 #[derive(Clone, Debug, Node)]
diff --git a/sv-parser-syntaxtree/src/declarations/task_declarations.rs b/sv-parser-syntaxtree/src/declarations/task_declarations.rs
index 278d9dc..2512acd 100644
--- a/sv-parser-syntaxtree/src/declarations/task_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/task_declarations.rs
@@ -57,7 +57,7 @@ pub struct TfPortItem {
         Vec<AttributeInstance>,
         Option<TfPortDirection>,
         Option<Var>,
-        Option<DataTypeOrImplicit>,
+        DataTypeOrImplicit,
         Option<(
             PortIdentifier,
             Vec<VariableDimension>,
@@ -78,7 +78,7 @@ pub struct TfPortDeclaration {
         Vec<AttributeInstance>,
         TfPortDirection,
         Option<Var>,
-        Option<DataTypeOrImplicit>,
+        DataTypeOrImplicit,
         ListOfTfVariableIdentifiers,
         Symbol,
     ),
diff --git a/sv-parser-syntaxtree/src/declarations/type_declarations.rs b/sv-parser-syntaxtree/src/declarations/type_declarations.rs
index a56a858..7fbee12 100644
--- a/sv-parser-syntaxtree/src/declarations/type_declarations.rs
+++ b/sv-parser-syntaxtree/src/declarations/type_declarations.rs
@@ -16,7 +16,7 @@ pub struct DataDeclarationVariable {
         Option<Const>,
         Option<Var>,
         Option<Lifetime>,
-        Option<DataTypeOrImplicit>,
+        DataTypeOrImplicit,
         ListOfVariableDeclAssignments,
         Symbol,
     ),
@@ -82,7 +82,7 @@ pub struct NetDeclarationNetType {
         NetType,
         Option<Strength>,
         Option<VectorScalar>,
-        Option<DataTypeOrImplicit>,
+        DataTypeOrImplicit,
         Option<Delay3>,
         ListOfNetDeclAssignments,
         Symbol,