ITIL is not positioned as a formal standard, and there is no such thing as certifying an organization to be ITIL compatible. Yet there is a need today for benchmarking the maturity of IT organizations against peers, and for commercial organizations to illustrate their respect of common practices. Training and certification of professionals is one way to deal with this. Alternatively, ISO 20000 is generally accepted as an international standard that can be used as a subset of ITIL for certifying organizations against. Or the other way around, ITIL would be the default approach for implementing an ISO 20000 compatible standard way of working. Multiple publications have been written on the compatibilities and incompatibilities between ISO 20000 and ITIL. Other frameworks that used to be combined with ITIL include Prince2 and PMBOK, CMM / CMMi, ISO9000 / quality management, Cobit, and others. The latest versions of ITIL have incorporated some of the key messages of these complementary frameworks.
Given this reality that ITIL is to be used in combination with other management theories, frameworks and standards, little practical guidance is embedded in the various sources on how to use them together. For instance, ITIL had 10 or 11 core processes in version 2, and it now has somewhere between 26 and much more processes in version 3 (2007/2011). ISO 20000 has 13 processes in version 2005 and between 13 and 17 in version 2011. Cobit has 34 processes, and MOF v3, MOF v4, ASL and BISL have yet others. All of them use different names and definitions, so their relevance is relative. There is no one truth, and inspiration from various sources including ITIL needs to be combined and applied on a particular situation in a creative and appropriate way.