You can refer to objects in the selection set by using the following syntax:
Where n is the number of the displayed object from the last query performed in the current session. For example, @1 refers to the first object, @2 the second object, and so on.
Where n and m are the numbers of displayed objects from the last query performed in the current session, and where m is greater than or equal to n. This syntax refers to the nth through mth object, inclusive. For example, @2-5 refers to the second through fifth object, inclusive; @3-@6 refers to the third through sixth object, inclusive.
This symbol refers to all of the objects in the query selection set.