Survex (and therion) source formats

Wookey wookey at
Mon Aug 22 11:47:51 BST 2016

On 2016-08-22 06:04 +0100, Olly Betts wrote:

[Re the default meaning of ',' in survex files]
> Hmm, I'm not keen on breaking existing data even if some self-selected
> subset of users think it's OK.
> I'd far rather find some way to address this that doesn't break existing
> data and also which doesn't take 20 years to execute.
> For example, we could release "Survex 2.0" which (as well as the current
> source format) also supported a new "version 2" of the source format,
> indicated by (say) "*version 2".  This could have a different default
> meaning for ",", and could clean up other stuff: finally drop all the
> long-deprecated stuff like "*prefix", actually enforce structure on
> commands like "*team" which almost everyone just seems to treat as a
> free-form text field (ignoring what the manual says should be in there)
> meaning it's hard to process them automatically now.

If we are thinking about an updated source format I think it's worth
thinking quite hard about therion compatibility. There was discussion
at Eurospeleo about the annoyance of having two very similar, but
incompatible, formats for what are arguably the two most popular
surveying tools: survex and therion.

If survex added a *centreline then it would be structurally equivalent
(and this is sensible to allow for future not-centreline data (walls,
point clouds?)).

Are you interested in at least having a discussion with the therion
people and survex users about using a common 'v2' data format? The
differences are so small it seems like something that should be
attainable, and could significantly improve workflows and reduce the
significant amount of time people spend munging data between

There will be some tricky issues about backwards compatibility and
whether change is worth it, but I think that if we are having some
change anyway, it's a great opportunity to try and re-merge the two
formats (where much of the difference is pretty gratuitous).

> Once Survex version 2 is suitably widespread, switching the default
> assumed version could be done in Survex 3.0, and anyone wanting to
> process old data with current Survex would only need to add "*version 1"
> at the top (or have a wrapper "*version 1" "*include oldfile.svx").

Marking files with some kind of format ID would be a very good idea anyway.

> Or a different file extension could be used to indicate the difference -
> "new.survex" vs "old.svx" for example.  The world has moved on from 8.3
> now...
> Not sure what's best, but I think we can find a way to achieve this.

Principal hats:  Linaro, Debian, Wookware, ARM
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