Versioning of namespaces is nearly always a mistake

Hi Folks,

There is a fascinating discussion taking place on the Saxon mailing list. Here is a recap:

Ryan McKinley wrote about the difficulties of creating XPath queries to 5 versions of DDMS (DoD Discovery Metadata Specification). He observed that it is difficult because each version of DDMS uses a different namespace, such as:

urn:us:mil:ces:metadata:ddms:4

urn:us:mil:ces:metadata:ddms:5

Ryan lamented: “I could create 5 different (but nearly identical) queries for each version.”

Michael Kay responded:

Versioning of namespaces is nearly always

a mistake, but it's a rather common mistake.