Keywords

A keyword for a command can be shortened to as little as one character as long as it can be distinguished from other keywords for that command.

For example, the keyword DATASET for the ALLOCATE command, can be shortened to any of the following:

DATASE
DATAS
DATA
DAT
DA

It cannot be shortened to the single character D, however, because another keyword for ALLOCATE, DDNAME, also begins with D and the two could not be distinguished.