Have a look at :
http://ez.no/developer/forum/setup_design/php_code_in_content http://ez.no/developer/forum/developer/how_to_insert_php_code_in_templates
And I was looking for a contribution I think which enabled to hack the kernel of ez and insert php code in online editor... But I don't refind it... I tell you as soon as get it.
On line one of the content section : it's written that content and design are separeted.
I guess it's a very bad idea to put PHP code in a content for this reason. If you want a code to be executed on a particular content, you can make a specific module or make an override and create a specific operator / function.
Another point is that as it's content, it won't neer be interpreted by the template engine...