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]

1
#
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.
2
#
The set of known registered character encodings contains every registered character encoding specified in the IANA Character Sets registry except for the following:
3
#
Each known registered character encoding is identified by an enumerator in text_encoding​::​id, and has a set of zero or more aliases.
4
#
The set of aliases of a known registered character encoding is an implementation-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.
5
#
How a text_encoding object is determined to be representative of a character encoding scheme implemented in the translation or execution environment is implementation-defined.
6
#
An object e of type text_encoding such that e.mib() == text_encoding​::​id​::​unknown is false and e.mib() == text_encoding​::​id​::​other is false maintains the following invariants:
  • (6.1)
    e.name() == nullptr is false, and
  • (6.2)
    e.mib() == text_encoding(e.name()).mib() is true.
7
#
Recommended practice:
  • (7.1)
    Implementations should not consider registered encodings to be interchangeable.
    [Example 1: 
    Shift_JIS and Windows-31J denote different encodings.
    — end example]
  • (7.2)
    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]