1099-B Adjustment codes - How to know what to use?

Trying to translate my 1099-B from from Vanguard to Turbotax. There are several Total Stock Mkt Idx Adm to Federal MM transaction. There are non-zero amts in box 1g for one of these. I elected to enter the summary instead of each individually. When I check the  TT box to say I need to enter the amount, enter the  amount TT wants me to provide 1 or more Adjustment codes. I am clueless as to how to choose these adjustment codes. I can find the list of accepted codes in the IRS documents, but nothing in the Vanguard form to tell me which one to use.

 

What am I missing?