Iqa‘ Aqsaq is very popular in the Muwashah vocal genre. It is 1 beat short of Iqa‘ Sama‘i Thaqil but sometimes it can be played immediately before or after a piece in that iqa‘ without interruption, during a Wasla.
An alternate form of Aqsaq replaces the rest on the 6the beat with another dum, thereby creating a sequence of 2 consecutive dum-s that evokes Iqa‘ Sama‘i Thaqil.