If you modify an Indus symbol by adding the dot of emptiness at each of the cardinal points, it signifies that information regarding the central statement is not known. This is the verb to
deliver or to meet combined with the adjective unknown. Hence, it is the adjective lost.
Illustrative Text Reference:
Lothal: Seal: L-48 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 249: Collections in India: Suomalainen Tiedeakatemia.
Indus Script Sign Number 7025: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.