Datatypes:

• We have agreed that some form of Jeremy's entailment is required (msg 0635 Feb)
• Patrick's entailment suggests that Jeremy's entailment works with Patrick's extra rules
• Jos has rules and a formal proof that Jeremy's entailment works with range and drange with ageA and ageB example - with extra rules
• Patrick suggests we only need one age property but this requires assuming a datatype class includes both value and lexical space members
• Patrick claims with some support from others that this also allows to do without drange
• Having to use two properties is ugly
• We have agreed that the datatype being a union of val and lex spaces is ugly