TagSupport has an internal Map storage that you can use. You can add Objects to that Map that you may need in your processing but, don't want to make a variable with getters and setters for. To add it you call the setValue(
String, Object) To get it, you can call getValue(String) and as with all Map's you can get all the Keys that where added to the Map you use getValues() This returns an Enumertion of the Keys to the Map (Kind of a misleading name, should be getValueKeys()).
This is useful when you need to have access in a child tag to an Object in a parent Tag but, don't want to have it available outside the Tags life cycle.