Mahadevan's sign number 26 is a composite character. The compound noun general porter 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 26 translates as 'general porter all areas'.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-130 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 43: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 26: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.