$ERR_NOTISM

56

Not an ISAM file

One of the following has occurred:

• You’ve attempted to open a file that is not recognized as an ISAM file.
• You’ve specified a channel in the GETRFA, POSRFA, ISKEY, or ISSTS subroutine that was not opened to an ISAM file.
• You’ve specified a file in the ISCLR subroutine that is not recognized as an ISAM file.
• You've attempted to open an ISAM file whose index and data headers don’t match, indicating that either another instance or revision of the file was copied over just one of the files (.ism or .is1), or one of the files has become corrupted.