Coin 1/4 Anna, British India, is in Numista only one without any subtype (# 447), but in Krause it's divided in three subtypes: #447.1 and #447.2 for copper, and #447.2a for silver. It has "verified sheet" mark, and I think it's not OK.
Variations are possible, in fact Numista has two different weights for this (copper) coin (1 for Bombay and 1 for Madras). But not sure if they ever had a silver 1/2 anna. The lowest denomination of silver coin in BI was 2 annas according to what I know.