Denies primary trump support.
All subsequent doubles are penalty.
4-level and double jump cues show a void in the cue suit. A direct raise of opener's suit tends to be pre-emptive. Double says all future doubles are penalty. Generally, if opponents make a two-suited overcall and both suits are known, cue of lower ranking suit is a good raise of opener's suit and a cue of the higher ranking suit shows a strong hand with the 4th suit. Maximum of say 12pts or slightly more if minor suit interest.