Thank you - you've just given me the last bit I've been mising on understanding '\G' (I knew about it, but had failed to produce useful code when I'd tried it before.) Much appreciated!

Unfortunately, with regard to this script, your implementation hits one of the restrictions that I stated: the "mangling" is so extensive that breaking up the text into the 'raw/cooked' bits and then processing each cooked bit (as opposed to the single chunk sans the raw bits) is too expensive, time-wise.

I'm slowly coming to believe that, given my particular requirements, the 'tag-and-reinsert' method may well be the best one. This is reinforced by the fact that there are modules out there that do the same thing (the [% foo.x %] syntax mentioned previously, etc.) Oh well...

Again, thank you for your response.