In the programmers' manual, I find:
The dig_plus file contains information that accelerates vector queries.
It is created by the program build.vect (which is run by v.digit when
a vector file is created or modified, and by v.support at user request)
from the data in the dig and dig_att files.For this reason, and since the internal structure of the dig_plus file
is complex, the format of this file will not be described.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Are there any plans to more explicitly document file formats? Perhaps man
pages such as:
dig.5 dig_ascii.5 dig_att.5 dig_cats.5 dig_plus.5 cell.5 cats.5
(I suppose the question is: Does anybody want to take on the task?)
I know that information exists in scattered places for most things,
but it can sometimes be frustrating to try to find it.
--Darrell