[Therion] infer plumbs

[Bruce]

>with -90/+90 have no effect too

With your example, true, I think, maybe.

But with this...

source
   survey test
     centerline
       infer plumbs on

       1 2 10 0 0
       2 3 10 90 -90
       3 4 10 0 0
       4 5 20 150 0
       5 6 10 270 90

       equate 1 6

     endcenterline
   endsurvey
endsource

export model
export map -projection [elevation 000 deg]

You will notice a difference in the outputs.
Try commenting out the infer plumbs line.
Try reinstating up and down.  I have added opposite bearings to the up and
down legs to give a contrasting effect to the situation where plumbs are
'off'.

Bruce