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

    Default: No image name     Value: File specification

    File name of a program to be invoked upon receipt of a connection
    request containing an address that matches one of the values
    contained in the set described by the addresses characteristic.

    Example:

    set session control application mirror -
       image name sys$system:net$mirror.exe