what is the rationale for "uio-howto.aux.xml" DocBook file?

[Robert P. J. Day]

  just noticed for the first time the in-kernel Doc file
uio-howto.aux.xml (sitting next to uio-howto.xml). the latter file is
the one processed by "make htmldocs", so what is the purpose of that
former one? i don't see where/how it's being picked up. any hints? am
i missing something painfully obvious?

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================