Chapter 02 · Section 2.1
Series
An option series consists of:
a) all options of the same type, traded for the same underlying asset, with the same exercise price and same expiration date.
b) all options of the same type, traded for the same underlying asset with the same exercise price.
c) all options of the same type, traded for the same underlying asset with the same expiration date.
I
Of three terms (type, class and series), series is the most restrictive. Actually, a series includes identical options.