A large fraction of the total effort invested in the design of XQuery by the working group has been focused on a relatively small number of “watershed issues.” These are issues whose resolution had a significant global impact on the language by influencing a number of related decisions. All of these issues are complex, and some of them were quite contentious. Eight of these watershed issues are discussed here; they are listed below.
Handling of untyped data. This issue deals with the kinds of operations that can be applied to data whose type is not known.
Unknown and inapplicable data. This issue deals with how unknown values can be encoded in XML and how various operators should be defined on these values.
What is a type? This ...