5 Character Set for Text
Text in Emacs buffers is a sequence of 8-bit bytes. Each byte can
hold a single ASCII character. Both ASCII control characters (octal
codes 000 through 037, and 0177) and ASCII printing characters (codes
040 through 0176) are allowed; however, non-ASCII control characters
cannot appear in a buffer. The other modifier flags used in keyboard
input, such as Meta, are not allowed in buffers either.
Some ASCII control characters serve special purposes in text, and have
special names. For example, the newline character (octal code 012) is
used in the buffer to end a line, and the tab character (octal code 011)
is used for indenting to the next tab stop column (normally every 8
columns). See Text Display.
Non-ASCII printing characters can also appear in buffers. When
multibyte characters are enabled, you can use any of the non-ASCII
printing characters that Emacs supports. They have character codes
starting at 256, octal 0400, and each one is represented as a sequence
of two or more bytes. See International. Single-byte characters
with codes 128 through 255 can also appear in multibyte buffers.
If you disable multibyte characters, then you can use only one
alphabet of non-ASCII characters, but they all fit in one byte. They
use codes 0200 through 0377. See Single-Byte Character Support.