As discussed previously, your editor can be invoked from within PMDF MAIL. This allows you, for instance, to use an editor when composing messages. As discussed in Section 7.9.1, there are two ways for you to express your choice of editor.
Normally, you instruct PMDF MAIL when to invoke the editor on a command-by-command basis with the /EDIT qualifier. However, when you invoke PMDF MAIL you can instruct PMDF MAIL to always invoke the editor for specific operations (e.g., send operations, reply operations, etc.). See Section 7.9.2 for details.
Finally, with the PMDF MAIL/EDIT=KEPT command, you can instruct PMDF MAIL to always use the same editor subprocess. PMDF MAIL will attach to the process for all editing operations. Information as to what input file to edit and output file to produce is passed to the editor subprocess via logicals in the LNM$JOB logical table. See Section 7.9.3 for details.