Data Over Cable Service Interface Specification

The idea is that an interface is not a class, it is just a specification of what classes that implement it must contain.

Ndis (network driver interface specification)

Software requirement specifications include both installation and maintenance requirements, and functional aspects of software that a user needs.

User requirement specification in software is the specifications about functional and user interface specification.

Extensive firmware interface is defined as a specification that originates from Intel. It defines the interface between platform firmware and the operating system. It tries to reduce dependence of the OS on the firmware implementation details.