Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide

APPEND

The APPEND option specifies whether an existing data set is to be extended or re-created.

Read syntax diagramSkip visual syntax diagram             .-Y-.
>>-APPEND--(-+-N-+-)-------------------------------------------><
 
Y
Specifies that new records are to be added to the end of a sequential data set, or inserted in a relative or indexed data set. This is the default.
N
Specifies that, if the file exists, it is to be re-created.

The APPEND option applies only to OUTPUT files. APPEND is ignored if:

Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide