As below…

>I've always like the idea of a "series" in bigger caves, i.e. a group of related passages that help divide the cave into neighbourhoods.

            Yes, we do that for larger caves.

>I pictured it as a bunch of building blocks (scraps and associated centrelines) that I could put together hierarchically

            I think it is.

>and that I could easy pass parameters from one level to the other or change parameters of one branch or another. In Walls and On Station it was super easy to change the colour of centreline for 2D or 3D display in a hierarchical manner, just right click on the appropriate  survey or folder (on Station) or Book (Walls). I used this a lot to visualize the cave. Eg make all newly surveyed passage pink, colour code passage by survey date [cannot], depth [can, for maps, not centreline]  etc. With my limited understanding of Therion, I've not yet been able to do this. goes now it is hard to subdivide parameters of a map. It seems like there should be some commands for this. e.g. if survey = Arch then colour = blue, if team includes "Rob Countess" then colour = yellow, if flag = lead then colour = pink, if flag = drafting in then scrap/map = blue, elseif drafting out then scrap/map = red, elseif oscillating then scrap = yellow, else if scrap = black. Actually that last one would be a useful visualization, now I want to do that. It should be easy to set labels to hide if font <7 pt, [can do this but it is a hack]

Mostly I would say these are very hard to do with Therion, if not impossible (but I would very much like some of them).  Think of Therion as ‘still in development’. You might need to get into some serious coding.  I get around it in a very limited kind of way by using multiple output formats at once.  ie maps and models in pdf, lox and 3d (survex viewer).

Therion output is produced by compiling what is effectively a batch of files, so you have to expect that it won’t have the immediacy of interactive software.

>In answer to your "why not walls": Well i really like some features of Walls. The blunder detection system is awesome.

            From your description I can now see why not Walls.  However I read about the blunder detection in Walls once, and was jealous.

>Plus I like being a gatekeeper for my projects. You get to stay up to date and to on and to a degree direct  whats going on in your pet projects. When I used On Station everybody knew how to use it. When I switched to walls only a few people knew how to use it.

            Ooh! A control freak. All the great ‘sole owner’ survey projects in NZ stall eventually (20-30 yr timeframe) because of overload or lack of succession planning.  The main reason I use something like Therion is that it allows simultaneous drawing by many people.  Share the load!  If you use version control, you can keep up with what others have done without necessarily doing any of the work.

>So Therion is, so far, absolutely the least user friendly cave mapping software around,

            Probably true I am afraid, but I am sure that could be solved if we get the right sort of instructions and examples.

Bruce