Mahadevan's sign number 66 is a composite character. The adjective calm or quiet is surrounded by four points of light. A speck 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 noun everywhere. Therefore, sign number 66 means that everywhere is quiet.
Illustrative Text Reference:
Gola Dhoro: New find: No CISI number: Hollow seal: Ancient Indus seal found at Gola Dhoro: Photograph (NB. the image has to be flipped in order to resemble a sealing): © Kuldeep Bhan: https://www.harappa.com/goladhoro/goladhoroseal.html: Accessed: 19 February 2016.
Comment:
In the example, the best translation is that everywhere is safe.
Image Credit:
Indus Script Sign Number 66: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.