The ASN.1 ABSTRACT-SYNTAX class is a useful class definition used to declare the top-level protocol data units (PDU's) defined within a specification. The class is described using the following ASN.1 definition:

   ABSTRACT-SYNTAX ::= CLASS {
      &id OBJECT IDENTIFIER UNIQUE,
      &Type,
      &property BIT STRING { handles-invalid-encoding(0)} DEFAULT {}
   }
   WITH SYNTAX {
      &Type IDENTIFIED BY &id [HAS PROPERTY &property]
   }

ASN1C is used to create a meta-definition for this structure. The definition is stored in the file Asn1AbstractSyntax.java (or Asn1XerAbstractSyntax.java for XER). An object created from the resulting Java class is populated just like any other compiler-generated structure for working with ASN.1 data.