CAAPE User's Manual - ALSTOM Signaling Inc.

General Rules and Techniques5. SECTION 5 – GENERAL RULES AND TECHNIQUES5.1. SYSTEM AND APPLICATION NAMESSystem and application names should be unique.5.2. SYMBOLSSymbols (also called variables) are used to name the input, output and internal valuesprocessed by an application. A symbol is a name that represents the value and ismeaningful to the user. Symbols are used to identify:• The physical input and output ports on I/O boards• The values that control the operation of a board - e.g. to determine when an outputflashes or pulses• The bits in an input or output message• The internal data used in logic equations - e.g. Current Result or Self Latched in VPI5.2.1. Symbol Naming RulesSymbols in CAAPE applications can be no longer than 16 characters in length. Theymust not start with the '@' character, since this character is used in certain reservedinternal names. Symbols must not contain embedded blanks, and they must not containany characters which can be used as delimiters in a compiler input file. For example, avariable that is used in application logic should not contain a ‘*’ or a ‘+’ character, sincethese characters represent the AND and OR operators in Boolean logic.P2512A, Rev. Oct/09 5–1 Alstom Signaling Inc.