[Therion] Selective display of survey lines

[Steve Clark]

On a related note to Alvaro's questions regarding show and hide of 
survey lines, I'm looking for some advice on the best way to handle the 
selective displaying of some survey lines, but not others.

We have a project surveying a mainly submerged (diving) cave. The vast 
majority of our survey stations and connecting lines are an actual 
continuous physical line in the cave (say 300 stations). Some stations 
(maybe 50) do not have physical lines connecting them (e.g. gaps/jumps 
in the line and dry disto survey).

We would like to be able to :

1. Produce a map with with no lines at all (seems easy, use 'symbol-hide 
line survey' & 'symbol-hide point station' )
2. Produce a map with only the physical lines shown, but not the other 
survey lines. This is as a resource for divers to show the line 
configuration and navigation etc. but not the other survey information.

What is the best way to achieve 2? I've considered making a user-defined 
line type 'u:caveline' and drawing it in all the scraps where submerged 
line exists. Then hide all survey lines and stations. This would be 
laborious but may give most flexibility.

Is this the best way or can anyone suggest an alternative approach?

Regards,

Steve Clark