@namespace(uri="general", prefix="general")
package general;

@namespace(uri="domain", prefix="domain")
package domain {

@gmf.diagram(foo="bar")
class Domain {
   val Block[*] blocks;
   val Street[*] streets;
   val basic.ExternalNode [*] externals;
}
@gmf.node(label="name")
  class Block extends basic.NamedElement {
    ref basic.ExternalNode [*] Port;
  }

@gmf.link(source="source", target="target")
  class Street extends basic.NamedElement {
    ref Block source;
    ref Block target;
   attr String sourceLabel;
   attr String targetLabel;
  }

}

@namespace(uri="basic", prefix="basic")
package basic {

  @gmf.node(label="name")
  class ExternalNode extends NamedElement {
  }

  abstract class NamedElement {
    attr String name;
  }

}