This Indus sign has two elements. The first is a pictograph of a mat with each short edge split into three units, which denotes a floor or pitch area with a width of three standard mats. A sun symbol has been added on one long edge. It indicates that the area was open to the sun. Hence, the first element is the noun courtyard.
The second element is a point of darkness, which the artist has placed in the centre of the courtyard. It is the adjective inner.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-1719 a: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 28: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1550: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.