* valList "contains one or more valItem elements defining possible values for an attribute"
* valItem "documents a single attribute-value within a list of possible or mandatory items."
This is misleading, because valList may be used for elementSpec just as well.
Additionally, both specs send the reader to section 22.4.5, "Attribute List Specification", only. They are not discussed elsewhere in ch. 22.
Moreover, the example in valItem is not very intuitive (and the one in valList shows an attribute definition, which is fine, but another one would be good to have, for elements).