US Patent 7487177 Set identifiers for objects

Set identifiers for objects are determined based on individual identifiers of the objects. A first identifier is received from a first identification tag associated with a first object. A second identifier is received from a second identification tag associated with a second object. A set identifier corresponding to a set of objects that includes the first object and the second object is determined, based on the first identifier and the second identifier. The set identifier is associated with a virtual object that corresponds to the set.