tion for TDMA Systems (includes EIA/TIA 553) IS 41 Cellular Radio Telecommunications Intersystem Operations (the TDMA variant of MAP in Appendix 2: Naming and Data Typing in AML Introduction This appendix provides a brief description of how data types and data values are specified and used in AML specifications. For more detailed information, see the ITU-T recommendation for ASN.1 (X.208) and AML documentation. The latter can be obtained from the author. Naming and typing of data is important in AML, e.g. in order to enhance the expressiveness of AML specifications. Names and data types are used in many types of AML specifications. The purpose of using names and types is to produce operational simplicity, to produce semantic simplicity and to support encoding of data in a design-language independent way (e.g. for creating the messages of protocols). For example, instead of defining a variable Size as just a 16-bit variable, one can declare it as a variable of four integer values: Size SINTEGER(2048I8192132768I131072 The type reference INTEGER refers to those operations that can be performed on the variable Size, and the set of possible values defines the value range of Size. The semantic value of expressions can be enhanced by adding an identifier that explains what the type is used for, as in this expression: SwithProp = SEQUENCE {switchSize Size, OtherProp} Often it is also valuable to give names to values, as e.g. the value name miniSwitch- Size to the value 2048 of the type Size: miniSwitchSize Size ::= 2048 Naming and typing in AML is based as much as possible on ASN. 1 (Abstract Syntax Notation One). The main reason for using an abstract language is that data can be represented in a way that is independent of any particular software language and operating system. ASN.1 was chosen because it is a standard that is specifi- cally designed for supporting message specification. A program operates on values that have a bit-representation. If the designer expresses data in (high-level) data types instead of in bit