type_spec

type_spec 
      ::= 
      datatype 
      | ( variable_name "%type" ) 
      | ( table_name "." column_name "%type" ) 
      | ( table_name "%rowtype" ) 
      | type_name 

This rule is call by

-> argument_type
-> field_spec
-> return_type
-> subtype_declaration
-> variable_type