Partial View of the UML Metamodel. A named rectangle represents a metaclass of the UML metamodel. Abstract metaclasses have their names in italics. A gray rectangle represents an interest element for the definition of our profile. A solid line connecting two metaclasses or connecting a metaclass to itself represents an association. A filled diamond at one end of an association (aggregation end) represents a composite aggregation association. A stick arrowhead at the end of an association represents a navigable end. Finally, a line with an hollow triangle as an arrowhead connecting two metaclasses represents a generalization.
Guardia et al. BMC Genomics 2012 13(Suppl 5):S3 doi:10.1186/1471-2164-13-S5-S3