<UML> new type of modelling element that extends the semantics of the metamodel

NOTE 1 to entry: Stereotypes have to be based on certain existing types or classes in the metamodel. Stereotypes may extend the semantics, but not the structure of pre-existing types and classes. Certain stereotypes are predefined in the UML, others may be user defined. Stereotypes are one of three extensibility mechanisms in UML.

NOTE 2 to entry: The stereotype may specify additional constraints and tag definitions that apply to model elements. In addition, a stereotype may be used to indicate a difference in meaning or usage between two model elements with identical structure.