Common Language Infrastructure

The Common Language Infrastructure (CLI) is an open specification and technical standard originally developed by Microsoft and standardized by ISO/IEC (ISO/IEC 23271) and Ecma International (ECMA 335)[1][2] that describes executable code and a runtime environment that allows multiple high-level languages to be used on different computer platforms without being rewritten for specific architectures.

Ecma and ISO/IEC require that all patents essential to implementation be made available under "reasonable and non-discriminatory (RAND) terms."

As of January 2013[update], neither Microsoft nor its partners have identified any patents essential to CLI implementations subject to RAND terms.

The kernel profile is actually a very small set of types to support in comparison to the well known core library of default .NET installations.

However, the conformance clause of the CLI allows for extending the supported profile by adding new methods and types to classes, as well as deriving from new namespaces.