This is a pictograph of a door or gate. The Indus symbol for a door or a gate is always two Indus units wide. This one is six Indus units tall.
Illustrative Text Reference:
Chanhu-daro: Seal: The Cleveland Museum of Art: The J. H. Wade Fund 1973.160: http://www.clevelandart.org/art/1973.160: Accessed: 26 February 2018.
In inscription reference 1973.160, the door of six units high is associated with one that is seven units high. It therefore takes on the meaning inner door, whilst the symbol that is seven units
high takes on the meaning outer door.
Indus Script Sign Number 1242: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.