5 Conformance

Conformance is of interest to the following audiences:

• Those designing, implementing, or maintaining C# implementations.
• Governmental or commercial entities wishing to procure C# implementations.
• Testing organizations wishing to provide a C# conformance test suite.
• Programmers wishing to port code from one C# implementation to another.
• Educators wishing to teach Standard C#.
• Authors wanting to write about Standard C#.

As such, conformance is most important, and the bulk of this specification is aimed at specifying the characteristics that make C# implementations and C# programs conforming ones.

The text in this specification that specifies requirements is considered normative. All other text in this specification is informative; that is, for information purposes only. Unless stated otherwise, all text is normative. Normative text is further broken into required and conditional categories. Conditionally normative text specifies a feature and its requirements where the feature is optional. However, if that feature is provided, its syntax and semantics shall be exactly as specified.

Undefined behavior is indicated in this specification only by the words ‘undefined behavior.’

A strictly conforming program shall use only those features of the language specified in this specification as being required. (This means that a strictly conforming program cannot use any conditionally normative feature.) It shall not produce output dependent on any unspecified, undefined, or implementation-defined behavior.

A conforming implementation of C# shall accept any strictly conforming program.

A conforming implementation of C# shall provide and support all the types, values, objects, properties, methods, and program syntax and semantics described in the normative (but not the conditionally normative) parts in this specification.

A conforming implementation of C# shall interpret characters in conformance with the Unicode Standard. Conforming implementations shall accept compilation units encoded with the UTF-8 encoding form.

A conforming implementation of C# shall not successfully translate source containing a #error preprocessing directive unless it is part of a group skipped by conditional compilation.

A conforming implementation of C# shall produce at least one diagnostic message if the source program violates any rule of syntax, or any negative requirement (defined as a “shall” or “shall not” or “error” or “warning” requirement), unless that requirement is marked with the words “no diagnostic is required”.

A conforming implementation of C# is permitted to provide additional types, values, objects, properties, and methods beyond those described in this specification, provided they do not alter the behavior of any strictly conforming program. Conforming implementations are required to diagnose programs that use extensions that are ill formed according to this specification. Having done so, however, they can compile and execute such programs. (The ability to have extensions implies that a conforming implementation reserves no identifiers other than those explicitly reserved in this specification.)

A conforming implementation of C# shall be accompanied by a document that defines all implementation-defined characteristics, and all extensions.

A conforming implementation of C# shall support the class library documented in Annex C. This library is included by reference in this specification.

A conforming program is one that is acceptable to a conforming implementation. (Such a program is permitted to contain extensions or conditionally normative features.)