OT Clean C standard?

[Patrick <spell_gooder_now@...>]

I am re-reading the Lua reference manual. I see that Lua is written in a 
subset of ANSI C and C++ known as clean C. I would like to improve my C 
code and what better way then to follow in the Lua developers footsteps 
but I can't find a references to this online. Could someone point the way?

Thanks for reading-Patrick