In response to Nigel's suggestion to make it clear than there is no requirement for a conforming implementation to actually use the CLI, I propose making the following change in Annex C Standard library, C.1 General (see the bold parenthetic sentence):

A conforming C# implementation shall provide a minimum set of types having specific semantics. These types and their members are listed here, in alphabetical order by namespace and type. For a formal definition of the types and their members identified in (§C.2), refer to ISO/IEC 23271:2012 Common Language Infrastructure (CLI), Partition IV; Base Class Library (BCL), Extended Numerics Library, and Extended Array Library, which are included by reference in this specification. (However, this does not require a conforming implementation to actually target the CLI.) For a list of types and their members required beyond those identified in §C.2, see §C.3}}.

The proposal sounds good - I'd remove the parentheses though.