specification devRepCnf(locinvid, {chAddr}, {refuse}, person, cause) FOHmess type information local values and global type information OPERATION chAddr ::=5 -operation identifier, OPid. PROPERTIES {,synch,,} COMMON TYPES Person::=person INTEGER (000101..991231) request (Person, AddrPar) AddrPar:=CHOICE{[0]PostCode, [1]StreetName, [2]StreetNumb} PostCode::= IA5String Size (6) StreetName ::= IA5String Size (20) StreetNumb ::= NumericString Size (10) confirm (Person) refuse (Person, Cause) Cause::=INTEGER{noSuchPerson (0), noSuchPostCode (1), ...) TIME CONSTRAINT ACTIVITY TIME 100 ms Fig. 5.25 A typed operation specification The language must include a predefined set of data types (integer, real, boolean, etc.) that are used to create user-defined types. ASN. is such a language, specifi- cally designed for telecom applications and for supporting the definition of user- defined types. The ASN.1-types used in this operation specification are CHOICE, INTEGER, IA5String and NumericString (see Appendix 2) However, AML also supports however also a set of AML-defined types. In addition, it is anticipated that users may want to define their own set of data types, which should be supported by the methodology, see Sect. 5.7.5. A specification of FOH messages controls the operation of the FOH. Figure 5.26 gives an example of a message specification. It describes a message format that can carry the information elements of an AML-ASP. A message specification is com- mon for all operations within an abstract protocol and open for new ones (in this case up, to 64 operations are supported). Note, however, that a message specifica- tion depends on the syntax for ASPs, which is defined by the language that is used for abstract protocol specifications. Thus, format handlers for supporting AML, IDL and ROSE are not compatible. A FOH message that carries AML-ASPs must include a value of an operation identifier (OPid) and of the actual primitive type (PrimType). Normally, the data type for operation identifier and primitive type is the s