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

    Default: None                        Value: File name

    Indicates the file name or command that is associated with starting a
    process for the represented application.

    Example:

    set x25 access application X25_MAIL file "sys$system:x25$mail.com"