Emacs has a lot of funny names.
The file etc/JOKES in the Emacs distribution contains a large number of these, as well as a generous assortment of other classical editor jokes. (Press C-h F to view the Emacs FAQ, then C-x C-f to look for the file etc/JOKES in the same directory as the FAQ file. You’ll also find some other funny files there.)
Use of the Meta key
From: KaiGrossjohann Subject: Re: My meta key is sometimes not my meta key Newsgroups: comp.emacs Date: Tue, 26 Jun 2001 13:59:58 +0200
Emacs looks for Meta_L and Meta_R keysyms in the output of “xmodmap -pm”. That will tell Emacs which modifier is the meta modifier. From then on, Emacs uses that modifier to mean meta. If there are no Meta_L and Meta_R keysyms in the output of “xmodmap -pm”, Emacs looks for Alt_L and Alt_R. If these aren’t there, either, you have to use ESC.
I forgot to mention that other programs always use the mod1 modifier for meta, regardless of the keysyms.