Valid selection criteria include expressions such as the following:
density < 9 and stiff > 10000
group in ('A', 'F', 'H')
log(x) >= 2
All standard arithmetic, comparison, and logical (Boolean) operators can be used, as well as a variety of other operators. See the section on the WHERE statement in SAS Language: Reference for more information. SAS functions described in that book can also be used in your criteria.
Note that if you specify conditions that span lines, a space (' ') is inserted when the lines are concatenated to form the selection criteria that are applied.