The Indus Dictionary Project
The symbol depicted in Mahadevan's sign number 1424 would have had a large and a small size in Indus script. However, only the smaller version is extant. Each size represented a different ideograph, and takes a different meaning.
The larger version of the sign equated to the Chinese character tián 田. It represented the division of a piece of land into fields. Hence, it was the noun field. Xu Shen said that the symbol looked like four enclosures complete with footpaths between the fields or rice paddies¹.
The smaller size is based upon the pictograph of a boundary stone. The addtion of four divisions creates an ideograph for the noun landmark.
Landmark: Mohenjo-daro: Seal: M-1976 a: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 93: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
There are two examples of Mahadevan's sign number 1424 in inscription M-1976. Both examples are half a character in height. They are positioned in the centre of the character area.
Indus Script Sign Number 1424: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.
1. Xu Shen, 121 CE: Shuowen Jiezi.