Process start variables

Hi! I can’t find any information about process start variables. Experimentally I managed to find that process start None events have empty local variables scope and root scope could be only extended by these events. On the other hand, the process Message start events local scope contains all the events passed with them and I could control the starting root scope. Could anyone clarify is it correct behavior or None events should have the possibility to control the root scope of variables by their output?