[Therion] Showing a lower scrap down a pit in an overlying scrap

[Bruce]

>So is the advantage of using two maps only so that you can present a
>subset of the survey (from the separate map) offset...
In this case yes.

>...or at a different scale or similar in the same output PDF?
Cannot do different scales in the same output pdf as far as I know.

> I've not yet got as far as
>working out how to combine multiple maps into one output document.

It's as easy as;
	select map1
	select map2
	select map3
in the thconfig file.  The resulting pdf will then have a layer for each of
the maps and for the surface image if you have one.  These layers can be
toggled visible or not by the user of the pdf viewer.

Aside from that, I use maps hierarchically the same way as we tend to do
with survey centrelines as a basic means of managing a project. Each section
of cave has its own map.  These maps are in turn collected into maps, then
these are in turn collected into a map of the whole cave.  Then perhaps a
map with several nearby caves and surface features.  You can choose to
export the map at the top of the 'tree' in which case you do not get a
layered pdf, or you can export a selection of maps below the top of the tree
to get a layered pdf.

I've tried to explain my understanding of it, somewhat unfinished, here
http://therion.speleo.sk/wiki/doku.php?id=bds#concepts 

Bruce