when converting unibyte text to multibyte. It also applies when
@code{self-insert-command} inserts a character in the unibyte
non-@sc{ascii} range, 128 through 255. However, the function
-@code{insert-char} does not perform this conversion.
+@code{insert} and @code{insert-char} do not perform this conversion.
The right value to use to select character set @var{cs} is @code{(-
(make-char @var{cs}) 128)}. If the value of
This variable provides a more general alternative to
@code{nonascii-insert-offset}. You can use it to specify independently
how to translate each code in the range of 128 through 255 into a
-multibyte character. The value should be a vector, or @code{nil}.
+multibyte character. The value should be a char-table, or @code{nil}.
If this is non-@code{nil}, it overrides @code{nonascii-insert-offset}.
@end defvar
sequence of bytes. As a consequence, it can change the contents viewed
as characters; a sequence of two bytes which is treated as one character
in multibyte representation will count as two characters in unibyte
-representation.
+representation. Character codes 128 through 159 are an exception. They
+are represented by one byte in a unibyte buffer, but when the buffer is
+set to multibyte, they are converted to two-byte sequences, and vice
+versa.
This function sets @code{enable-multibyte-characters} to record which
representation is in use. It also adjusts various data in the buffer
codes cannot occur at all in multibyte text. Only the @sc{ascii} codes
0 through 127 are truly legitimate in both representations.
-@defun char-valid-p charcode
+@defun char-valid-p charcode &optional genericp
This returns @code{t} if @var{charcode} is valid for either one of the two
text representations.
(char-valid-p 2248)
@result{} t
@end example
+
+If the optional argument @var{genericp} is non-nil, this function
+returns @code{t} if @var{charcode} is a generic character
+(@pxref{Generic Character}).
@end defun
@node Character Sets
This function returns the charset property list of the character set
@var{charset}. Although @var{charset} is a symbol, this is not the same
as the property list of that symbol. Charset properties are used for
-special purposes within Emacs; for example, @code{x-charset-registry}
-helps determine which fonts to use (@pxref{Font Selection}).
+special purposes within Emacs; for example,
+@code{preferred-coding-system} helps determine which coding system to
+use to encode characters in a charset.
@end defun
@node Chars and Bytes
In multibyte representation, each character occupies one or more
bytes. Each character set has an @dfn{introduction sequence}, which is
normally one or two bytes long. (Exception: the @sc{ascii} character
-set has a zero-length introduction sequence.) The introduction sequence
-is the beginning of the byte sequence for any character in the character
-set. The rest of the character's bytes distinguish it from the other
-characters in the same character set. Depending on the character set,
-there are either one or two distinguishing bytes; the number of such
-bytes is called the @dfn{dimension} of the character set.
+set and the @sc{eight-bit-graphic} character set have a zero-length
+introduction sequence.) The introduction sequence is the beginning of
+the byte sequence for any character in the character set. The rest of
+the character's bytes distinguish it from the other characters in the
+same character set. Depending on the character set, there are either
+one or two distinguishing bytes; the number of such bytes is called the
+@dfn{dimension} of the character set.
@defun charset-dimension charset
This function returns the dimension of @var{charset}; at present, the
@result{} (latin-iso8859-1 72)
(split-char 65)
@result{} (ascii 65)
-@end example
-
-Unibyte non-@sc{ascii} characters are considered as part of
-the @code{ascii} character set:
-
-@example
-(split-char 192)
- @result{} (ascii 192)
+(split-char 128)
+ @result{} (eight-bit-control 128)
@end example
@end defun
@result{} 2176
(char-valid-p 2176)
@result{} nil
+(char-valid-p 2176 t)
+ @result{} t
(split-char 2176)
@result{} (latin-iso8859-1 0)
@end example
+The character sets @sc{ascii}, @sc{eight-bit-control}, and
+@sc{eight-bit-graphic} don't have corresponding generic characters.
+
@node Scanning Charsets
@section Scanning for Character Sets
@end defvar
@defvar save-buffer-coding-system
-This variable specifies the coding system for saving the buffer---but it
-is not used for @code{write-region}.
+This variable specifies the coding system for saving the buffer (by
+overriding @code{buffer-file-coding-system}). Note that it is not used
+for @code{write-region}.
When a command to save the buffer starts out to use
-@code{save-buffer-coding-system}, and that coding system cannot handle
+@code{buffer-file-coding-system} (or @code{save-buffer-coding-system}),
+and that coding system cannot handle
the actual text in the buffer, the command asks the user to choose
another coding system. After that happens, the command also updates
-@code{save-buffer-coding-system} to represent the coding system that the
+@code{buffer-file-coding-system} to represent the coding system that the
user specified.
@end defvar
@defun coding-system-list &optional base-only
This function returns a list of all coding system names (symbols). If
@var{base-only} is non-@code{nil}, the value includes only the
-base coding systems. Otherwise, it includes variant coding systems as well.
+base coding systems. Otherwise, it includes alias and variant coding
+systems as well.
@end defun
@defun coding-system-p object
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