The Indus Dictionary Project
This ideograph is comprised of the end of an area; the beginning of an area; a track, and; an arrow indicating the direction of travel. You should note that the arrow is positioned midway along the track. The orientation of the arrow, when combined with the track gives us the verb to approach. Thus, we can deduce that the location is midway between the end of one area and the beginning of another. In other words, this Indus sign represents the noun threshold.
Mohenjo-daro: Seal: M-331 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 84: Collections in India: Suomalainen Tiedeakatemia.
This is Mahadevan's sign number 156, which I have redrawn to better reflect the original.
Threshold: Lynn Fawcett, 2017.