11.   I hesitated, then opened the file and started to read.

12.   This routinely takes the form of file numbers which are allocated centrally, by the accounts department, when the file is opened.

13.   You must have opened a file using OPENOUT, OPENIN or OPENUP before you use this statement.

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

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

16.   Consequently, it is possible to successfully open a file on a full device.

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

18.   Before you use this statement, you must have opened a file using OPENOUT or OPENUP.

19.   Consequently, the only time the operating system refers to a file by its name is when it opens the file.

20.   In order to do this you must OPEN the file for use.