sch-rnd - use cases 
 The "back annotation" 
 Setup 
	-  any <-> sch flow
	
-  in a later phase of the project, in a 3rd party software (e.g. PCB layout tool, simulation software) some change is made that has to be carried back to the schematics
 Problems 
	-  net change: multiple ways a network connection can be specified
	
-  net change: hierarchy; what if a schematics is used in 4 instances and there's a change only in one instance?
	
-  attribute change: attributes may be calculated by plugins (source shall be changed)