Example of Open statement:

Illustration:

The OPEN INPUT TRANSACTION, OLD-MASTER OUTPUT NEW-MASTER.

The illustration represents that there are two input files named the TRANSACTION and OLD-MASTER and one output file known as the NEW-MASTER.  All these files are opened and these are prepared for reading or writing.

Illustration:

OPEN INPUT MARK-FILE.

OPEN OUTPUT RESULT-FILE.

The first OPEN statement opens the MARK-FILE in the input mode and the file is ready for the reading.  The later statement makes the RESULT-FILE ready for the writing. There may be numerous OPEN statements in a program.