There are a lot of Martins! Thank you all who responded. I'll spend some time and digest the information, and check it out in due course. Martin B came up with one of the key pieces of information that I'd seen before but forgotten.
This is a special intermediate format which can be easily imported into xtherion:
* added import functions for PocketTopo export - centerline in text editor - File->Import->PocketTopo therion export - sketches in map editor - Backgroud Images->Insert->PocketTopo therion export
There are some issues, but most of the features are supported.
The toporobot website is a bit of a challenge for a lowly English speaker, but luckily the "toporobot method" page has lots of pictures, so I get the drift. This numbering system will cause some consternation over here, because we usually use lettered prefix's to describe the survey year and trip/team. I guess I'll have to convert letters to digits. Thanks again Bruce