The RDML preprocessor will preprocess C and Pascal files that
    contain RDML statements. There are two methods that allow you to
    specify the language type of the source file:

    1. Use a language qualifier when invoking the RDML preprocessor

    2. If you do not specify a language qualifier, the RDML
       preprocessor will attempt to determine what language the
       source file contains by looking at the file extension supplied
       in the command line. If the file extension is ".RC", RDML will
       assume the file is a C file. If the file extension is ".RPA",
       the RDML preprocessor will assume the file is a Pascal file.

    An error message will be produced if the RDML preprocessor can
    not determine what language is to be associated with a specified
    input file.