In this Indus sign, the outline of the container is softened to give us a pictograph of a bag. Hence, it is the noun bag.
Illustrative Text Reference:
Desalpur: Seal impression: Dlp-3 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 355: Collections in India: Suomalainen Tiedeakatemia.
Comment:
In inscription Dlp-3, the bag is used to carry a bow and arrows.
Image Credit:
Indus Script Sign Number 8071: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.