The function fn:available-system-properties returns a sequence of qnames. At the bottom of its section (bottom of 20.4.5), there's a convenience-function described to convert these into strings that can be used with system-property.

While that's a good thing, the function is introduced with:

"However, they must first be converted to the form expected by the system-property function. This can be conveniently achieved by passing a QName to the function:"

I think it is more accurate to say that this *may* be needed. While the function returns qnames, we can't say anything about their prefixes, but processors are allowed to assign prefixes (right?). In such cases it may be enough to simply cast the qname to a string.

With the caveat that the prefix in the string may get out of namespace-scope.

But bottom line is, either we should be more explicit as to why we go through the trouble of giving a utility function to the user, or we should settle with "may":

"However, they may first need to be converted to ..."

(alternatively, can't we request the F&O group to introduce an fn:qname-to-eqname function? It is so weird we have introduced eqnames, but no function at all to handle them)