Ok, I did a google search and got tired of wading through the old messages with no answer.
I'm fixing the obvious shortage of dog holes in an old work bench I bought. I've done the top justice. It was a lot of work to disassemble and set up the top on a drill press with support stands. So I want to do anything else I can think of before putting it back together (like properly mounting the original vise that came with it).
I see some ready-made work benches and the pictures of the Veritas twin screw vise showing dog holes on the apron at the front edge of the bench. I'm having a little trouble seeing the value of these if you have a respectable vise and bench slave installed on the front of the bench already. But I don't want to read about some really great use for extra holes only 24 hours after I put the bench back together.