The Indus Dictionary Project
This Indus sign is comprised of two mats set within a room. The sign is topped with two sedge plants in a way which suggests that the room also has sedge mat room dividers.
It may be that such sedge mat rooms were used for sleeping.
Mohenjo-daro: Seal: M-1187 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 140: Collections in Pakistan: Suomalainen Tiedeakatemia.
Note the similarity of the sedge symbol to that in Champollion's Egyptian sign number 221 (left), which he describes as a type of garden, and which I would suggest depicts a cultivated sedge bed.
Furthermore, Champollion describes his sign number 344 (right) as a reed pen or qalam. However, the pictograph is actually a papyrus sedge plant. Therefore, it is the writing surface and not the pen, which gives us the association with writing.
The Indus Civilisation's sedge symbol may represent madurkathi, a type of sedge, which is still used for mat making in West Bengal.
Sedge Mat Rooms: Lynn Fawcett, 2020.
Champollion's sign number 221: Jean-François Champollion le Jeune, 1841: Dictionnaire égyptien en écriture hiéroglyphique: Chapter 4: Manuscript Page 210: Firmin Didot, Paris.
Champollion's sign number 344: Ibid. Chapter 6: Manuscript Page 301.