trlib is the transformation library originating at the Danish Geodetic Institute, GI, in the 1960s. It includes official transformations for Danish, Faroese and Greenlandic reference systems.
The library is declared final at version 1.1
Version 2.0, also present in the code base is an abandoned “future” version.
trlib functionality is currently being reimplemented as part of the (much more widespread) PROJ.4 library. https://github.com/OSGeo/proj.4/
Also, see OSGeo/PROJ#388 for some initial discussions specificly targeting preparations for trlib reimplementation.
Comments and requests regarding trlib and KMSTrans2 may be sent to grf@sdfe.dk