A recent property buyer encountered an issue where the vendor's thumb impression wasn't accepted at the Sub-Registrar's Office (SRO), leading to the use of a middle finger impression. Experts confirm that while thumb impressions are standard, other finger impressions are also valid if a thumbprint cannot be taken. The registration process relies on multiple factors beyond just fingerprints, including physical presence and official seals, making a document registered by the SRO legally sound and irrefutable.