Methods and systems for decoding a picture. A method includes receiving a coded video stream including a picture partitioned into first sub-picture units, the first sub-picture units including one first sub-picture unit, and an additional first sub-picture unit including a first ordered second sub-picture unit, from among second sub-picture units of the additional first sub-picture unit, and a last ordered second sub-picture unit, from among the second sub-picture units of the additional first sub-picture unit. The method further including decoding the picture, the decoding including obtaining index values of the first ordered second sub-picture unit and the last ordered second sub-picture unit of the additional first sub-picture unit, without the coded video stream explicitly signaling any of the index values and a difference value between the index values of the first ordered second sub-picture unit and the last ordered second sub-picture unit to the at least one processor.