DbForms contains limited support for foreign keys within database schemas. DbForms does currently not check foreign key constraints or start cascading actions like updating foreign keys within a referencing table whenever the key of a referenced row is updated. But:
There is support to express foreign keys within dbforms config file.
Foreign key information is available within running web application to be used by servlets or JSPs.
Devgui tries to include foreign key information automatically within dbforms config file by using JDBC metadata methods
Some of the stylesheets used by devgui to automatically generate JSPs use foreign key information from config file. So they are able to generate select tags etc. to allow the user to choose from rows within another table.