Section 3(g) in Kerala General Sales Tax Rules, 1963
(g)"Month" means a calendar month;(ga)"private key" means the key of a key pair used to create a digital signature;(gb)"public key" means the key of a key pair used to verify a digital signature and listed in the digital signature certificate;(gc)"Quarter" means a period of three months commencing on the first day of April or the first day of July or the first day of October or the first day of January in each year.
