I have seen notation like this before and usually the "B" means bet. If that is the case, then Carcass bet, num raised, and Carcass folded.

I believe that posting blinds is not included in notation like this, but we can tell that Carcass was the one who acted first, making him/her the small blind.

It may be something that is unique to LHE, but the database could have considered a call from the small blind as a bet.

This is how I think the hand went assuming a normal two blind structure, let me know what you think.

1. Carcass posts $5 small blind
2. num posts $10 big blind
3. Carcass calls the big blind
4. num raises to $20
5. Carcass folds

This is how I think the hand went assuming a normal two blind structure, let me know what you think.

1. Carcass posts $5 small blind
2. num posts $10 big blind
3. Carcass calls the big blind
4. num raises to $20
5. Carcass folds

If it is a one blind structure then the database hand would be more straightforward, but that kind of structure is rare.