Malt Lot Analysis and Specialty Malt question

[TheNegotiator]

I have read about how to calculate the 100% efficiency of a grain bill to be used to compare against your own measured mash efficiency. I went on to read about Malt Lot Analysis sheets and using the Dry Basis Extract Percentage numbers on the sheets to calculate the 100% efficiency of the specific grains you are using.

I went to calculate a theoretical grain bill I put together and when I went to the Malt Lot Analysis sheet I found no numbers listed under the Dry Basis Extract Percentage for some of the grains (chocolate malt, black malt, and roasted barley to name a few). I did some more research and found that these grains aren't usually given DBFG and DBCG numbers because they usually don't account for that much of the grain bill.

I looked on HBT's Malt Chart and BeerSmith and noticed that these grains had SG Potential and Yield Percentage Numbers. How were these numbers determined if you can't get the DBFG and DBCG numbers for these grains? And where can I find these number so I can calculate the Potential and Yield Percentage Numbers for a specific maltster's specialty grain?

I thought I found some ten page two column research article on the subject, but I didn't have time to read it and decided to read it at a later time. Now I can't remember where I saw it.

Thank you in advance.