PPI Articles & Presentations

Read interesting and informative short articles relevant to systems engineering and projects.

Making Sense of the OCD, CONUSE, OpsCon, CONOPS Alphabet Soup


Making sense of the OCD, CONUSE, OpsCon, CONOPS alphabet soup

Understandably, a great deal of uncertainty and confusion is evident regarding these OCD, CONUSE, OpsCon, CONOPS similar-looking terms associated with system development. Let’s try to clarify.

We will commence with “today’s” definitions that are represented by contemporary standards and guides such as ISO/IEC/IEEE 15288:2015 and the INCOSE Systems Engineering Handbook 4th Edition. I will then share with you some history that has contributed greatly to the confusion surrounding these terms. 

OCD, CONUSE, OpsCon, etc.

OCD, CONUSE, OpsCon are alternative names for the same set of information, a system-centric description of intended use of an item in terms of users and their relevant characteristics; uses for each user; and for each user and use, how it is to be used; together with the external conditions intended or expected during use. This information serves primarily as a reference for evaluation of fitness for intended use, otherwise called validation.

The origins:

  • OCD – Operational Concept Document or Description, has its origins in the USA defence-aerospace industrial/government complex, leading to publication in 1992 of an OCD guide by the American Institute of Aeronautics and Astronautics (AIAA), followed by publication of guides of USA defence and commercial origin, all under the name OCD.
  • CONUSE – Concept of Use, conceived by the United Kingdom Ministry of Defence and used within its military capability development process.
  • OpsCon – Operational Concept, conceived by the International Council on Systems Engineering (INCOSE) in 2015, and published in the 2015 edition of its Systems Engineering Handbook, to which can be added
  • CONEMP – Concept of Employment, a UK MoD early, lean CONUSE with a focus on identification of users and uses, essentially in support of a business case.
  • SoI – Statement of Operating Intent, a term widely used in military operational circles as distinct from engineering, and essentially the same thing again.
  • IUD – Intended Use Description, a term encountered in the Medical Device sector.

The public domain OCD standards to varying degrees suggest other content for an OCD peripheral to intended use, a result of the “all things to all people” and “lowest common denominator of agreement” phenomena characteristic of standards development. See ANSI/AIAA G-043B-2018, Guide to the Preparation of Operational Concept Documents, as the best of the public domain OCD guides, also invoked by the current ISO standard ISO/IEC/IEEE 15288:2015, Systems and software engineering — System life cycle processes. See also my own Project Performance International (PPI) OCD guide PPA-000950-17, Operational Concept Description (OCD)

CONOPS – Concept of Operations

A CONOPS is an operational solution description, a description of that part of the solution that serves an end-use purpose in providing an enterprise, business or military capability. The description is in terms of key solution elements, their key characteristics and the concept of their interoperation to achieve key Capability/Enterprise/Business outcomes. The term is only used for systems that are a mixture of humans and technology (usually) or entirely human (occasionally). This term with this meaning has been in widespread use for many decades in many parts of the world. For a guide to content, see my own Project Performance International (PPI) OSD (Operational Solution Description) guide PPA-004023-7, Concept of Operations (CONOPS)/Operational Solution Description) OSD).

Some Relevant History

In 1998, IEEE, by accident, released a new standard, IEEE 1362-1998 – IEEE Guide for Information Technology – System Definition – Concept of Operations (ConOps) Document, with content for an OCD (description of intended use). As you would expect, this use of the same term for fundamentally different sets of information led to rapidly growing confusion. Until in 2011 IEEE, to its credit, recognized what a mess it had created, working with ISO and INCOSE (who had also become implicated in the mess) to sort it out. The offending IEEE standard was cancelled, and in 2015 the ISO/IEC 15288:2008 standard was cancelled, replaced by ISO/IEC/IEEE 15288:2015 which reinstated OCD and CONOPS to their original meanings. In a similar timeframe, INCOSE reinstated OCD and CONOPS to their original meanings in replacing its Systems Engineering Handbook 3.2.2 with the 4th  Edition, while inventing the term OpsCon as yet another term meaning a “description of intended use”. Unfortunately, much confusion remains.

A Recommendation

Well-chosen language is clear as to meaning and is not easily mutated. For my small part in the evolution of engineering practice, I recommend:

CONUSE, for a description of intended use.

OSD (Operational Solution Description) for what was originally, and now again can be called, CONOPS.

Have you ever faced some misunderstandings or confusion while using one of those terms? How have you and your colleagues solved it? Please share your ideas – I am pleased to hear about your experiences and thoughts.


Published By

Systems engineering thought leader, consultant, trainer and coach, impacting people's lives on six continents.
Published 3 years ago


FREE Monthly SE Industry News?
Scroll to Top