\xmlatt{}{} has a counterpart \xmlattribute{}{LPATH}{} where one can start the search for the attribute at LPATH.
for \xmlchainatt{}{} I am missing such a counterpart \xmlchainattribute{}{LPATH}{} where one can do the same.

The problem now is that \xmlchainatt{#1}{att} always finds attribute att when it is defined on the node itself.
But consider the case where att="true" exists with the intention to trigger a search higher up in the call chain for that same attribute att.
Of course \xmlattribute{#1}{..}{att} is not exactly the same as \xmlchainattribute{#1}{..}{att} would be .

yours sincerely
dr. Hans van der Meer