“…• First it should be acknowledged that in the work of Zhou [44], Zhou and Zhang [45], they used exactly the same multirank as r 4 to explain congruences mod 5 for 4colored partitions of type (1, 2), (1, 3) and (2, 3) respectively, so our Theorem 3.6 below can be viewed as a natural complement to their work and shows the full power of r 4 . • Secondly, this definition of r 4 entitles us to consider a natural rank-preserving bijection between P [c,d] and P [d,c] : (π r , π b , π y , π o ) → (π y , π o , π r , π b ).…”