11.   An investigation has been started and it will continue until, well, the file is closed.

12.   Any data still in the file buffer is written to the file before the file is closed.

13.   However, if you wish to CLEAR the variables, it is simpler if you close the data files first.

14.   You should also close data files before chaining another program.

15.   CHAIN does not automatically close data files, but it does clear the variables in which the file handles were stored.

16.   However, STOP does not close data files.

17.   However, the file must be closed in order to ensure that all the data written to it is physically written away to the file.

18.   If you do this, you must remember to CLOSE the file when you have finished with it in order to update the directory entry.

19.   Open the file, throw away the first line, read the line to be edited and close the file.

20.   When the file is closed, the directory is updated to show the maximum used length of the file.