{ index-set }

The index set expression returns the set of members of an index set. This expression is distinguished from a set constructor (see the section Set Constructor Expression) because it contains a list of set expressions.

The following statements use an index set with a selection expression that excludes the value 3:

proc optmodel;
   put ({i in 1..5 : i NE 3}); /* outputs {1,2,4,5} */