[Therion] Disconnected centrelines - Extended Elevation Control

[Olly Betts]

On Sat, Apr 08, 2017 at 11:32:00AM +0200, Martin Sluka via Therion wrote:
> 8. 4. 2017 v 10:46, Bruce Mutton via Therion <therion at speleo.sk>:
> > Both options feel a little bit like hacks.
> 
> Nosurvey is nosurvey.

The thbook defers to the Survex manual for the definitions of the data
styles ("See Survex manual for details.") and the Survex manual says:

    A NOSURVEY survey doesn't have any measurements - it merely indicates
    that there is line of sight between the pairs of stations.

Adding NOSURVEY legs where there isn't a line of sight (or even a passage
without an exact line of sight) is definitely a hack.

Cheers,
    Olly