8
Well, I've to say 'no'.
This is a smarty code there are many of these tags that would have to be in a faq, try a search in the XoopsFAQ for 'smarty'.
So, I don't remember where I've se the greater 'anatomy of the default theme' (probably wiki..), in that article you can find many usefull informations.
Also, open the default theme.html with an html editor, the code is commented so you can find something (just use a bit of logic).
P.S. <{$xoops_showcblock}> == 1 -> when any center block is displayed.
Regards,