Connectors show labels by default in Unified Modeling
Language (UML) diagrams. You can hide or show labels on all connectors
or selected connectors and restore default label locations after
you move them.
The types of labels that adorn a connector depend
on the type of connector and the settings for the properties of
its underlying relationship. For example, labels that adorn association
connectors can include labels for names, stereotypes, and multiplicity.
However, name labels appear only if you specify the associated property.