Documentation:OCLOperators excluding

excluding ( object : T ) : Collection(T)

Returns a collection containing all elements of self minus all occurrences of object. Note: at the time of writing, the OCL standard library sports a bug that changes *OrderedSets* in *Sets* when excluding elements.

Expression	Result
Sequence{'b', 'a', 'b', 'c'}->excluding('b')	Sequence{'a', 'c'}
Bag{'b', 'a', 'b', 'c'}->excluding('b')	Bag{'c', 'a'}
OrderedSet{'b', 'a', 'b', 'c'}->excluding('b')	Set{'c', 'a'}
Set{'b', 'a', 'b', 'c'}->excluding('b')	Set{'c', 'a'}

The opposite - to add an object to a collection - is Append.