Problem understanding set-register syntax

[Aurélien Bottazzini]

Hello everyone,

in my init.el I have

(set-register ?i '(file . "~/.emacs.d/init.el"))

which allows me to quickly jump to my init file using C-x r j i

But I don't really understand the syntax.

Why do I have to use the exclamation mark when I set the register?

Why can't I just use:

(set-register i '(file . "~/.emacs.d/init.el")) ; will say Symbol's value as variable is void:i

I tried to search in the documentation for set-register and variable definition but I did not find

anything to really explain it.

Thanks for any help.

Aurélien