- (void) addIndex:(ULONG)index

- (void) addIndexes:(OBIndexSet *)other

- (void) addIndexesInRange:(OBRange)range

- (void) removeAllIndexes

- (void) removeIndex:(ULONG)index

- (void) removeIndexes:(OBIndexSet *)other

- (void) removeIndexesInRange:(OBRange)range

- (void) shiftIndexesStartingAtIndex:(ULONG)index by:(LONG)delta