I just got off the phone with Ted Clutter, a case worker at the BATF in W. Virginia
Here it is:
Engraving specs:
Depth- .003" or greater
Size- 1/16" or greater
Location- Area not easily concealed or obstructed
Must include the following- Name of registered owner or corporation
city and state of owner or corporation
Caliber and model # (on most lowers
this info already exists)

RLT is acceptable in place of "Revocable Living Trust" (most people tell you it is not, but I will believe an ATF agent over most people when it comes to this)

Enjoy!