This standard defines the terminology, concepts and models for industrial automation and control systems (IACS) security. It establishes the basis for the remaining standards in the ISA99 series.

To fully articulate the systems and components the ISA99 standards address, the range of coverage may be defined and understood from several perspectives, including:

a) range of functionality included

b) specific systems and interfaces

c) criteria for selecting included activities

d) criteria for selecting included assets