VMS Help SCA, SCA Topics, Callable Routines, SCA$INITIALIZE, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 command_context
    type:       $SCA_COMMAND_CONTEXT
    access:     write only
    mechanism:  by reference

    SCA command context value to be initialized. This value is passed
    as an argument to other SCA$xxx routines.