Pools
Pools represent collections of a resource, typical things like Health, Money, Experience, etc.
Pools are more transactionally safe and work off 'change records' rather than absolute updates, as such they are best used for things that have +/- changes applied mostly.
Pools can be incorporated into Character Attributes and are usually declared to be of a 'type'.
At present the main use is multiple XP pools of type Experience, but this will grow over time.