IMPs, white vs. red, consider this hand.
♠ 3
♥ KJ1076
♦ Q10542
♣ Q2
RHO opens 2♠. You pass of course, as taking action here shows values. LHO then bids 4♠, back to you.
LHO could be strong but you don't win events by passing hands like this. You'd like to compete in a red suit without getting partner too excited with a strong hand.
Double ostensibly shows support for the unbid suits and 4NT shows the two lowest unbid suits, but in either case here when you remove the expected 5♣ to 5♦ you're showing the two highest unbid suits. This is not a named convention that I know of, rather bridge logic and, it seems, common expert practice.
Bridge World Standard discusses this under Conversions and indicates 4NT shows a weaker hand. That makes sense as double leaves partner the option of a penalty pass. 4NT would be my call here.