A linear traverse can be any straight line along which fracture data has been collected. This includes a borehole. For the purpose of applying the Terzaghi weighting, a borehole can be treated as a linear traverse in Dips. Therefore use Traverse Type = Linear (not borehole, which is only meant for oriented core data).
The orientation of a linear traverse (Orient1/Orient2 in the Traverse Information dialog) is always defined by Trend/Plunge i.e. Orient1 = Trend (or Azimuth) of borehole, Orient 2 = Plunge (or dip) of borehole. The plunge is measured from the horizontal (so a vertical hole would have plunge = 90 degrees).
If you had a perfectly straight borehole (i.e. no deviation) then you could define the entire borehole as a single linear traverse. Since boreholes are usually curved to some degree, we recommend that you split up the borehole data into a few “approximately” linear sections, as necessary. Then define each of these sections as a separate linear traverse. Note: theoretically, you could take the exact borehole orientation at each fracture measurement, and use this as the traverse orientation for each fracture, but then you would have to define a separate traverse for every single data entry, which would be quite tedious and unnecessary. Keep in mind that the Terzaghi weighting correction is not an extremely precise method, it is really just a convenient approximation. So, if you split up your borehole data into a few different sections, each of which has approximately the same orientation (within a few degrees), this should give you an adequate solution.