Thank you so much David for you help on this.

So yes, the instruction are lacking; David said he will give me a hand on it :)

Reza, what's the version of your database ?
I only tested it on Apache 3 and 5 so it can be probable that the function CONCAT doesn't work with every database.
Anyways, these 2 queries are only there to help you with the configuration of your sites and are not obligatory....

define('DIR_WS_HTTPS_CATALOG', '/a/');


if you want, you can have only one comment the categories' description like that
<!--site1-site2-site3-->

If you don't write any comments, the categories wont be displayed.