type 2; category 2; second class
Used as a prefix to classify things into a second type or category, often in technical, legal, or official contexts.
This document is handled as second-class mail.
I will get a Type 2 electrician license.
second-class mail
type II telecommunications carrier
Compound of 第二 (second) and 種 (type, kind). The exact historical derivation is uncertain, but the combination is a straightforward Sino-Japanese classificatory term.