■ More than one condition can cause this error:
 
  • A sequential-output-mode OPEN statement has been executed
    for a file that is already open.
 
  • You tried to open two different files using the same file
    number. For example:
 
              OPEN "A.TXT" FOR OUTPUT AS #1
              OPEN "B.TXT" FOR RANDOM AS #1
 
  • A KILL statement refers to an open file.
 
  • The file named in an ISAM OPEN FOR statement is already
    open for ISAM.
 
  • A file with the same name as the file argument in an ISAM
    OPEN FOR statement is already open for another access
    mode.
 
■ If you need additional help, move the cursor to a keyword
  and press F1 to open the Help window.