The Indus Dictionary Project
In Mahadevan's sign number 4035, the important man is placed in the centre of the symbol for river. Hence, the definition is the important man's river.
Mohenjo-daro: Tablet in bas-relief: M-481 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 115: Collections in India: Suomalainen Tiedeakatemia.
Mohenjo-daro: Tablet in bas-relief: M-1418 B: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 191: Collections in Pakistan: Suomalainen Tiedeakatemia.
The inscription on tablet M-481 is, unfortunately, quite badly degraded. However, on side A, it is clear that an offering is being made to the river. This suggests that Mahadevan's sign number 4035 may have been a proper name.
Indus Script Sign Number 4035: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.