WHERE-IS-FILE

@WHERE-IS-FILE Check whether a file is opened and / or reserved. Also list the user or RT program who has opened or reserved the file. Rules:
 * : file name. and must be unique.
 * 1) Permitted for all users.
 * 2) The possible messages are:
 * : OPEN BY USER ON TERMINAL 
 * : RESERVED BY RT-PROGRAM
 * (a peripheral file is reserved but not opened).
 * : FREE TO USE
 * : OPEN BY USER RT ON TERMINAL 1
 * (if opened by an RT program).

Example: @WHERE-IS-FILE (SCR)SCRATCH08:D SCRATCH08:DATA: OPENED BY USER GUEST ON TERMINAL 39 @