I was confused by the 4 digit code too, even after looking at a walkthrough. Then I realized the purpose of the asterisks (or stars); it involves what asterisks are mainly used for in math.

Decent escape, neither your best nor your worst. For the record, there ARE clues for every puzzle.

I had to look at the walkthrough to get thru some of the puzzles. there was no clues how to get the code for one of the cabinets.