This is a glyph for the beginning of an area, which is surrounded by three points of darkness and one point of light. The point of light is situated in the cardinal direction east. Hence the
condition is true in the east and false elsewhere. The translation is therefore, the noun eastern domain.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-1721 a: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 29: New material, untraced objects, and
collections outside India and Pakistan: Suomalainen Tiedeakatemia.
This is Mahadevan's sign number 1074, which I have redrawn to better reflect the original.