From Field System Programmer Reference Manual (Himwich, 1993):

The pfmed program is used to edit and manipulate the procedure file libraries. It may be started from a shell prompt. A semaphore is used to coordinate access to the procedure libraries between boss and pfmed. This allows procedures to be edited even while they are in use. All changes that a user makes in an active procedure library are saved until the operator exits from pfmed. Then the next time boss is scheduled the changes are picked-up. In order to prevent file handling problems between pfmed and boss there are two special restrictions: the Field System cannot be started or stopped while pfmed is active and operator may not change the active procedure library with either a proc= or schedule= command while pfmed is running.

1. Log on to the Field System machine assigned to the telescope where you want to edit the procedure
2. type pfmed
3. Active procedure files and procedure file currently open in pfmed are given at startup
4. type help for a list of available commands.
5. type exit when finished so that any changes are applied
6. New/changed procedures are now implemented