When you have more than one different type of
RWCollectable stored in an
RWCollection, you can't use a sorted
RWCollection. For example, this means that if you plan to store
RWCollectableStrings and
RWCollectableDates in the same
RWCollection, you can't store them in a sorted
RWCollection such as
RWBTree. The sorted
RWCollections are
RWBinaryTree,
RWBTree,
RWBTreeDictionary, and
RWSortedVector.
The reason for this restriction is that the comparison functions for sorted
RWCollections expect that the objects to be compared to have the same type.
