Emacs groups all supported characters into disjoint charsets.
Each character code belongs to one and only one charset. For
historical reasons, Emacs typically divides an 8-bit character code
for an extended version of ASCII into two charsets: ASCII, which
covers the codes 0 through 127, plus another charset which covers the
“right-hand part” (the codes 128 and up). For instance, the
characters of Latin-1 include the Emacs charset
ascii plus the
Emacs characters belonging to different charsets may look the same,
but they are still different characters. For example, the letter
‘o’ with acute accent in charset
latin-iso8859-1, used for
Latin-1, is different from the letter ‘o’ with acute accent in
latin-iso8859-2, used for Latin-2.
There are two commands for obtaining information about Emacs
charsets. The command M-x list-charset-chars prompts for a name
of a character set, and displays all the characters in that character
set. The command M-x describe-character-set prompts for a
charset name and displays information about that charset, including
its internal representation within Emacs.
To find out which charset a character in the buffer belongs to,
put point before it and type C-u C-x =.