[Nml-wg] New schema

I've just updated the schema to include PortGroups and LinkGroups and list all relations that Jeroen recently send out to the list. https://forge.ogf.org/sf/go/doc15481 Note that per UML standards, all abstract classes are now in italics. The source document can be found in the Subversion repository. I also added a schema that detailed the Relations as opposed to the class hierarchy. https://forge.ogf.org/svn/repos/nml-base/sources/NML-schema.graffle https://forge.ogf.org/svn/repos/nml-base/NML-schema.pdf https://forge.ogf.org/svn/repos/nml-base/NML-relations.pdf Feedback is most appreciated (did I forget something, are there any errors or omissions?) Regards, Freek