I know the current Space.Class_objectNumber_propertyName is very fragile, but forbidding underscore in class/property names is not am option IMO because it's very common. This is just an example I've seen yesterday: [``screen_resolution``](https://github.com/xwiki-contrib/application-angularjsdemo/blob/master/src/main/resources/Phones/PhonesClass.xml#L124) but I'm pretty sure there are more. We need to make it work as much as possible. I think we can build a regular expression that matches most of the valid request parameter names. Something like ``PREFIX_\d+_SUFFIX`` where SUFFIX is something along the lines of ``Util.isValidXMLElementName()`` and PREFIX can be '.+' but could also ensure the class name is valid (taking into account the space name can contain anything).