All field keywords beginning with html_form_ are passed directly into the form hash.
Thus,
they are really defined in form.tt which ships with Gantry.
html_form_foreign applies only when the field's html_form_type is display.
It indicates that this field is a foreign key and foreign_display should be used to get a human readable value to display instead of showing the rather meaningless foreign row id.
Note that this keyword is usually used when two different versions of a form are presented depending on the context.
The base form uses html_form_type select and html_form_foreign is ignored.
Later,
another form is displayed (to a less priviledged user) which uses html_form_type display.
The form type is usually switched with the Gantry::Utils::FormMunger.
To see an example, build:
bigtop -c example.bigtop all
Change to the newly created Kids directory and look in the form method in lib/Kids/GEN/Child.pm. Note the use of data statements to populate the table. See the pod for Gantry::Utils::FormMunger for a more natural approach.
