"heiko.braun(a)jboss.com" wrote : I am wondering why the schema contains element declarations for concrete activities like 'email'. IMO we shouldn't treat the stock activities anyhow different as the ones user supply. That means they wouldn't be represented by an element name on it's own. jPDL is an executable process language. Each node is of a certain type. One node type will delegate to an activity implementation (== direct mapping to the PVM construct). Another node type will call a java method through running a script or evaluating an expression. Other node types do more functional behaviour like email. Separating the structure from the activity behaviour would make the XML a lot more verbose and hence less readable. "heiko.braun(a)jboss.com" wrote : On the other hand, if we move stock activities to a custom namespace, then they are separated from the core xsd constructs. using separate namespaces for user defined node types is certainly something that i think should be possible. but a whole process should be usable without namespaces as well, i think. just referencing the core jpdl xsd in the default namespace is simple. so that should never be a problem. but combining namespaces is what always should be optional. meaning. the functionality should always be available with or without setting up the namespaces properly. so when users want to add a new node type, i don't want them to be forced to write an xsd and configure the namespace in the process. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4159466#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...