(xemacs.info)Intro to Keystrokes
2.1 Keystrokes as Building Blocks of Key Sequences
Earlier versions of Emacs used only the ASCII character set, which
defines 128 different character codes. Some of these codes are
assigned graphic symbols like `a' and `='; the rest are control
characters, such as `Control-a' (also called `C-a'). `C-a' means you
hold down the <CTRL> key and then press `a'.
Keybindings in XEmacs are not restricted to the set of keystrokes
that can be represented in ASCII. XEmacs can tell the difference
between, for example, `Control-h', `Control-Shift-h', and `Backspace'.
A keystroke is like a piano chord: you get it by simultaneously
striking several keys. To be more precise, a keystroke consists of a
possibly empty set of modifiers followed by a single "keysym". The set
of modifiers is small; it consists of `Control', `Meta', `Super',
`Hyper', and `Shift'.
The rest of the keys on your keyboard, along with the mouse buttons,
make up the set of keysyms. A keysym is usually what is printed on the
keys on your keyboard. Here is a table of some of the symbolic names
left mouse button
middle mouse button
right mouse button
upstroke on the left mouse button
upstroke on the middle mouse button
upstroke on the right mouse button
Use the variable `keyboard-translate-table' only if you are on a
dumb tty, as it cannot handle input that cannot be represented as ASCII.
The value of this variable is a string used as a translate table for
keyboard input or `nil'. Each character is looked up in this string
and the contents used instead. If the string is of length `n',
character codes `N' and up are untranslated. If you are running Emacs
under X, you should do the translations with the `xmodmap' program
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