System options are instructions
that affect the processing of an entire SAS program or interactive
SAS session from the time the option is specified until it is changed.
Examples of items that are controlled by SAS system options include
the appearance of SAS output, the handling of some files that are
used by SAS, the use of system variables, the processing of observations
in SAS data sets, features of SAS initialization, and the way SAS
interacts with your host operating environment.