It is possible to link a Note element to another element's internal documentation. This enables you to externalize model documentation to the diagram level, and as Enterprise Architect keeps the note and the internal structure in synch, you do not have to worry about updating the note contents; this is done automatically.
In the example below, two notes are linked into an element's internal structures. One is linked to an attribute, and displays the attribute name and notes. The other is linked to a constraint, showing the constraint name and documentation.