PropertyHandle :: Minus - Subtract collections

The result collection contains all instances that exist in the first but not in the second operand collection. The existence of an instance in a collection can be checked based on the sort key (passing YES for ik_opt ) or on local identities (LOID). Using the LOID is save but comparing the key is much faster. Hence, the key check should be used whenever possible.

Calling the function with one operator creates the difference collection between the calling (first operand) and the passed collection and stores the result in the calling collection.

Otherwise the operation is performed with the passed operand collections storing the result in the collection referenced by the calling property handle. When the calling property handle refers to a non empty collection all instances are removed before performing the operation. When the calling property handle is empty the function creates a temporary extend for storing the result.