Mahadevan's sign number 250 is a composite character. The noun method or way is surrounded by four points of light. A point of light denotes that something is true. It follows that a point of light at each of the cardinal points is an ideograph for the adverb everywhere. Therefore, sign number 250 means to be the custom or practice everywhere.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-1369 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 179: Collections in Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 250: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.