common. There are doubts whether the Indus script records a written language or is instead a system of non-linguistic signs or proto-writing similar to merchant's marks and house marks, and to the contemporary accounting tokens and numerical clay tablets of Mesopotamia. Due to the brevity of inscriptions, some researchers have questioned whether Indus symbols are even capable of expressing a spoken language. The spoken Harappan language has not been identified, so, assuming it is a written language, the language the script is most likely to express is unknown. However, an loanwords in the Rigveda may provide evidence of substrate language(s) which may have been spoken in the region of the Indus civilisation. No bigraphic or bilingual texts, like a Rosetta Stone, have been found. No names, such as those of Indus rulers or personages, are known to be attested in surviving historical records or myths, as was the case with rulers like Rameses and Ptolemy, who were known to hieroglyphic decipherers from records attested in Greek. Over the years, numerous decipherments have been proposed, but there is no established scholarly consensus. The few points on which there exists scholarly consensus are the right-to-left direction of the majority of the inscriptions, numerical nature of certain stroke-like signs, functional homogeneity of certain terminal signs, and some generally adopted techniques of segmenting the inscriptions into initial, medial, and terminal clusters. Over 100 (mutually exclusive) attempts at decipherment have been published since the 1920s, and the topic is popular among amateur researchers. Dravidian language Although no clear consensus has been established, there are those who argue that the Indus script recorded a Dravidian language. Early proponents included the archaeologist Henry Heras, who suggested several readings of signs based on a proto-Dravidian assumption. Based on computer analysis, the Russian scholar Yuri Knorozov suggested that a Dravidian language is the most likely candidate for the underlying language of the script. The Finnish scholar Asko Parpola led a Finnish team in the 1960s–80s that, like Knorozov's Soviet team, worked towards investigating the inscriptions using computer analysis. Parpola similarly concluded that the Indus script and Harappan language "most likely belonged to the Dravidian family". A comprehensive description of Parpola's work up to 1994 is given in his book Deciphering the Indus Script. Supporting this work, the archaeologist Walter Fairservis argued that Indus script text on seals could be read as names, titles, or occupations, and suggested that the