Library /sys$common/syshlp/nclhelp.hlb set, x25_access, application, user  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: No user ID                Value: Latin1String

    Default user identification to be used to start the application
    process. This attribute is not valid for type X29 login and
    should be null.  On OpenVMS, Latin1Strings must be embedded in
    quotes.

    Example:

    set x25 access application X25_MAIL user "X25MAIL"