Functions in SDF-P have the following characteristics:
Functions are called by means of a function name.
The result of a function is obtained from the input parameters.
Exactly one result value is returned.
The result value is inserted at the position of the function call.
The SDF-P scope of supply includes “predefined functions” (also called “built-in” functions) with which the user can process variables and strings or request information on the current system environment. For this purpose, SDF-P also supports functions which the system administrator creates via a special Assembler interface.
This chapter describes, first, general aspects of the use of functions, i.e. how they are called, etc.; and secondly, the factors which must be taken into consideration when the system administrator writes his/her own functions.