Section 202(1) in The Indian Post Office Rules, 1933
(1)For the purpose of preferential treatment in sorting transmission and delivery, postal articles are divided into the following four group in the following order namely:-(a)Postcards, Letter cards, Money orders and standard envelopes as defined in sub-rule (4) of rule 8.(b)Letters (other than standard envelopes as defined in sub rule 4 of rule 8) and surcharge air-mail articles.(c)Standard articles as defined in sub-rule (5) of rule 8;(d)all other postal articles.
