Possible Duplicate:
Why do LaTeX internal commands have an @ in them?
What do \makeatletter and \makeatother do?
What is the difference between \myname and \my@name while writing a .cls file?
I have tried a few times to write/understand other peoples packages. Though I'm no good yet, I keep running into a definition using @ or @@ in the name. Why is this done ? Is there any special meaning ? Is this in any way related to the use of _ and __ in python, where a variable starting with @ shouldn't really be messed with while one with __ definitely should not be messed with ?
As an example :
\@author is used in the class files article.cls but is not defined anywhere. So I assumed the @ to mean it was some kind of command internal to LaTeX/TeX. While in a custom class file (res.cls by Michael DeCorte to be exact) I've seen \@name is specifically defined as both
\def\name#1{\def\@name{#1}}
and
\def\@name{}
To my knowledge the latter ensures a default value is set up in case the \name command is not used by the document writer. But this still doesn't indicate why the @ is used.
