Hi guys FYI I’ve added a rule to http://dev.xwiki.org/xwiki/bin/view/Community/ApplicationDevelopmentBestPra… “ Put an XClass definition in a document by itself and refrain from having both the XClass and an XObject using it in the page. It's makes for better separation of concern but also helps for upgrades and solves some dark magic issue (a.k.a bug emoticon_smile) with XWiki import which could import the XObject before the XClass and cause some havoc… “ Let me know if you don’t agree. Also feel free to edit to improve the reasoning ;) Thanks -Vincent