PERFORM … …
Yes. Redefines just causes both fields to start at the same location. For example: 01 WS-TOP PIC X(1) 01 WS-TOP-RED REDEFINES WS-TOP PIC X(2). If you MOVE ’12’ to WS-TOP-RED, DISPLAY WS-TOP will show 1 while DISPLAY WS-TOP-RED will show 12.
CONTINUE is like a null statement (do nothing) , while NEXT SENTENCE transfers control to the next sentence (!!) (A sentence is terminated by a period)
Can rewrite(record length must be same), but not delete.