/PARAMETER_EXPAND=TPU_procedure_prefix

    Lets you customize calling sequences. Normally LSE uses a fixed
    algorithm to produce the appropriate placeholder definitions
    from the DEFINE PARAMETER command. If the default algorithm is
    inadequate, then you can supply explicit VAXTPU procedures to
    produce the DEFINE PLACEHOLDER command that you want.

    The argument provided with the /PARAMETER_EXPAND qualifier must
    be the prefix of a VAXTPU procedure name. Whenever LSE expands a
    parameter, it concatenates this prefix and the current language
    name, and looks for a VAXTPU procedure by that name.