Essential rules

The following rules MUST be followed.

1. The file should consist of 80-byte records. Consequently, no more than 80 characters per line are allowed.
2. There should be no non-alphanumeric characters (carriage returns, line feeds, etc.) anywhere in the file.
3. The last command in the file must be END.
4. The filename must consist of 8 alphanumeric characters or less, starting with a letter, and must have the extension .CAT.
5. There should be no more than 200 objects in the file, as this is the maximum number that can be held in memory at once.