We can't make them inherit as it doesn't make too much sense. At most we 
could make an interface, but that doesn't really help us lot and is 
likely to get in the way.

The duplication of ARGINFOs here is part of the WIP, and is likely to 
change. Atleast I might move the arginfo to the share part as well but 
annoyingly it uses "static" (enforced by PHP :-( )