Hi,
Sorry, I posted a little too fast for my question I found the answer 
here<http://wiki.contextgarden.net/Titles>http://wiki.contextgarden.net/Titles. 
Nevertheless, thank you for your response speed.
As I said before, I slowly migrates to ConTeXt (which I love!), Without 
abandoning LaTeX, which explains my confusion in the use of the command.
Regards,
Fabrice