Pricing Rule Sets ID Question

There was a Price Rule Set issue today that I realized the correct 'set' wasn't associated with the MOS. Easy enough. 

However, there was a set (formerly?) associated with that mode of sale. The only thing visible was the ID "28". 

Anytime I've seen this, I assume that set was inactivated or deleted... but I'm assuming the sets are numbered on a table somewhere. I couldn't find any IDs on the actual rule set page, and searching documentation, I couldn't find which table they'd have been stored in. 

Can I find out what rule set 28 was, and is there an audit trail anywhere for it? 

Thanks in advance!