10 REM FILE TEST
20 OPEN 1, 8, 4, "TESTFILE,SEQ,W"
30 IF ST <> 0 THEN PRINT "FILE ERROR"
40 IF ST = 0 THEN PRINT "FILE EXISTS"
50 CLOSE 1

MISSING FILENAME

ERROR: #8QJS7TQZAZ5RYDC45T6ZW1KZ95XX0VQQ