Can you swim? How long you will read that book? Can you hold on horse?

The reading and writing skill gives a "bonus" to reading speed, despite PPH rules where reading and writing is impossible.

This library gives -164 as a "bonus" to reading speed, which means 100 years. The reason is mostly technical - because returning something is easier and more clear than nothing (by null or exception), and partly because its logical - after ten years you have a chance to decode that strange symbols, especially when they mean something in a language you already know.

Skills are all the person skills on one pile. -> SameTypeSkills are skills of same type, like physical, on one pile -> Skill is specific learned "ability", like horse riding -> SkillRank is a "level" of the skill => SkillPoint is the only but required price of a SkillRank

SkillPoint is the currency unit for a SkillRank, composed from specific values, in specific combinations -> BackgroundSkillPoints are standard value given by first level -> ProfessionLevel is a level increment, cary-ing a property increment, which provides a skill point -> two SkillPoint(s) of type(s)-different-than-paid-one can be used for trade of new SkillPoint

Checks if payments haven't been used more times elsewhere: (that should check at least Skills as the final aggregator, or better every aggregator on the way)

SkillPoint

• BackgroundSkillPoints - check their total usage against their availability by \DrdPlus\Background\BackgroundSkillPoints::getSkillPoints
• ProfessionLevel - there is nothing to check, on every level can be obtained plenty of skill points
• cross-type SkillPoint as a payment - has to be unique, therefore no one else can use it, for payment nor as standard skill point

SkillRank

• SkillPoint has to be unique in whole universe, see SkillPoint cross-type payment check

Skill

• can be used just as an arbiter due its aggregating meaning
• can check if BackgroundSkillPoints are not overused should not check it, its too tricky, let it to Skills
• can check if SkillPoint and SkillRank are unique locally
• can check if cross-type SkillPoint(s) as a payment are unique and not used as a standard point locally

SameTypeSkills (can sum all the first and next levels skill ranks)

• can be used just as an arbiter due its aggregating meaning

CombinedSkills + PhysicalSkills + PsychicalSkills (has ability to find out unused skill point values of same-type skills)

• all the same-type skills it aggregate have to be unique in whole universe

Skills

• CombinedSkills + PhysicalSkills + PsychicalSkills has to be unique in whole universe
• should be the final arbiter, recommended way is to re-use existing checks of sub-aggregates