[text.encoding.general] (original) (raw)
28 Text processing library [text]
28.4 Text encodings identification [text.encoding]
28.4.2 Class text_encoding [text.encoding.class]
28.4.2.2 General [text.encoding.general]
A registered character encoding is a character encoding scheme in the IANA Character Sets registry.
[Note 1:
The IANA Character Sets registry uses the term “character sets” to refer to character encodings.
— _end note_]
The primary name of a registered character encoding is the name of that encoding specified in the IANA Character Sets registry.
The set of known registered character encodings contains every registered character encoding specified in the IANA Character Sets registry except for the following:
- NATS-DANO (33)
- NATS-DANO-ADD (34)
Each known registered character encoding is identified by an enumerator in text_encoding::id, and has a set of zero or more aliases.
The set of aliases of a known registered character encoding is animplementation-defined superset of the aliases specified in the IANA Character Sets registry.
The set of aliases for US-ASCII includes “ASCII”.
No two aliases or primary names of distinct registered character encodings are equivalent when compared by text_encoding::comp-name.
How a text_encoding object is determined to be representative of a character encoding scheme implemented in the translation or execution environment isimplementation-defined.
An object e of type text_encoding such thate.mib() == text_encoding::id::unknown is false ande.mib() == text_encoding::id::other is falsemaintains the following invariants:
- *e.name() == '\0' is false, and
- e.mib() == text_encoding(e.name()).mib() is true.
Recommended practice:
- Implementations should not consider registered encodings to be interchangeable.
[Example 1:
Shift_JIS and Windows-31J denote different encodings.
— _end example_] - Implementations should not use the name of a registered encoding to describe another similar yet different non-registered encoding unless there is a precedent on that implementation.
[Example 2:
Big5
— _end example_]