The correlation to the Western calendar was made two centuries later by Hendrik Doeff, himself opperhoofd of Dejima from 1803 to 1817, and an anonymous Japanese interpreter. They hypothesized that the person it had been issued to, jiyakusu-kuruun-heike, corresponded not to Specx but to Groenewegen (; Japanese medial [w] was written h at the time).
The connection to the Western calendar was established two centuries later by Hendrik Doeff, who served as opperhoofd of Dejima from 1803 to 1817 and an anonymous Japanese interpreter. They proposed that the recipient, jiyakusu-kuruun-heike, did not correspond to Specx but rather to Groenewegen (; during this period, Japanese medial [w] was written as h).