This is a pictograph of a rope stretched between two points of different heights. It is the noun zip line.
Illustrative Text Reference:
Mohenjo-daro: Copper Tablet: M-1548 A: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 428: Collections in Pakistan: Suomalainen Tiedeakatemia.
Comment:
In inscription M-1548, the symbol for zip line is perfectly aligned with the symbol for suspend, and the whole is executed in such a way that it actually looks like someone crossing a ropeway with their goods.
Image Credit:
Indus Script Sign Number 130: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.