> User-defined structures would be more beneficial if
> we could do this sort of thing:
> %p/%[ID:::%n%q:%n%q].%t
> 

Humm.. kind of non trivial thing to do (the function is not really reentrant)

But I will implement one day a more extended syntax ; such as:

--structure-match 'www.foo.com/*?q=' '%p/bar%[q:::].%t'
--structure-match 'www.bar.com/*?p=' '%p/foobar%[p:::].%t'
..

The matching syntax will be identical to scan rules one.

This is IMHO the "clean" way to handle this -- that is, controlling the build
structure according to some patterns.