Major Resource.xsd:
For the next two items, all resources are extensions of resource:PowerResponseType on line 156, so these comments apply to all resources.
Cardinality of emix:constraints: since all elements of emix:ConstraintsType are 0..n, what is the cardinatlity of emix:constaints at the higher level in ResourceLoadReductionType? Looking at the schema it is not at all obvious. Given the nillable discussions, and the empty tags from xcal, as written this may require empty tags. (it does seem that wherever the abstract baseConstraint is extended that minoccurs="0". I think an explanation in the guide to the schemas would make this less confusing on first read)
Possible recursion in definition of (e.g.) emix:constraints. As shown on line 22 the definition of ResourceLoadReductionType contains emix:constraints, which in turn includes emix:constraints. Is this a problem?
Line 19: missing colon inside "resourceRegulationService" should be "resource:regulationService" (it's a top-level element)
Line 65 "Regulation Product" comment - it's called a Service elsewhere. But isn't this a Regulation RESOURCE?
Line 66 and 68 - why is this called a "regulation service"? This is an information model. In the spec line 708 this is called Regulation Products, and the section heading line 697 is "Ancillary Services Product Descriptions". There may be no good way of addressing this, alas.