4.2.5 Command Line Definition and Environment

  For program execution the command line can be generated from a symbolic description passed to a specific key of the rule. The working directory, input, and output parameters can be accessed as special symbols in the command line definition. The following syntax is used for command line arguments:

Additional information can be passed to the program with environment variables. An environment definition can be

1. A string or symbol. If the symbol start with a ``$'', the value is taken from the current environment of VMake else an environment variable without value is create.
2. A list of a string or symbol and an associated value. The possibles values are:
   
   

The environment under VMS is divided into symbols and logical values. The definitions made by VMake are always logical values in process local table. This has the advantage that they can be used as device name from within the program. Since empty logicals are not allowed in VMS an empty string is assigned in this case.