1.   The file must have already been opened for output and the file handle stored in fnum.

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

3.   You can still access the open file if you used one of the static variables to store the file handle.

4.   A function which opens a file for reading and returns the file handle of the file.

5.   A function which opens a file for writing and returns the file handle of the file.

6.   A function which opens a file for update and returns the file handle of the file.

7.   This number is called the file handle.

8.   When you open the file, a file handle is returned by the interpreter and you will need to store it for future use.

9.   The open commands are, in fact, functions which open the appropriate file and return its file handle.

10.   You use the file handle for all subsequent access to the file.