This symbol is a combination of the verbs to indicate and to obscure. It is equivalent to an archaic version of the Chinese character wèn 文, for which Xu Shen gave the definition: 'wrong picture'. Modern definitions include the verbs to conceal; to gloss over, and; to cover up.
Illustrative Text Reference:
Harappa: Tablet - incised: H-1319 A: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 170: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
Comments:
This is Mahadevan's sign number 138, which I have redrawn to better reflect the original.
There is only one extant example of this Indus sign.
The inscription on tablet H-1319 appears to be a token for carriage hire. This suggests that, in context, the word conceal may have referred to a curtain.
Image Credit:
To Conceal: Lynn Fawcett, 2017.