This function places the number of longwords (VAX only) or
    quadwords (Alpha only) in the argument list into count. The
    value returned in count is the number of longwords (VAX only)
    or quadwords (Alpha only) in the function argument block not
    counting the count field itself.

    If the argument list contains items whose storage requirements
    are a longword (VAX only) or quadword (Alpha only) of memory
    or less, the number in the count argument is also the number of
    arguments. However, if the argument list contains items that are
    longer than a longword (VAX only) or a quadword (Alpha only),
    count must be interpreted to obtain the number of arguments.
    Because a double is 8 bytes, it occupies two argument-list
    positions on OpenVMS VAX systems, and one argument-list position
    on OpenVMS Alpha systems.

    This function is specific to Compaq C for OpenVMS Systems and is
    not portable.