My partner is from Pakistan and has a 5-year US visitors visa. On our last trip to the US, he was only given 30 days in the country (the CBP agent was a jerk on a power trip; since we were leaving in 15 days and had the tickets to prove it, the length of visa above 15 days was irrelevant). Since I'm a US passportholder I don't know the details, but I think he entered on an I-94W, right?