In UML diagrams, operations that function as queries
provide ways to observe the state of a system. You can specify that
an operation is a query if it returns a value, but does not change
the state of a system.
To specify an operation as a query:
In the diagram editor, click an operation.
In the Properties view, click the General tab.
On the General page, in the Qualifiers field,
select the Query check box.