You can define templates for custom display of your custom
fields; templates are available for: the Event Entry form,
Event Popup windows, the List View "details" column,
notification Mail, and RSS feeds. (See the
Templates settings page.)
If a field is marked "Required", new events will not be
accepted unless a value is set for that field.
For Popup Menus, a value of - will be ignored. (That's a
single hyphen.) You can include this as a choice and make it
the default value for a required field - this will require that the
user make a valid choice from the popup menu, instead of
defaulting to any particular choice.
The "Label" and "Display Order" are not used if an output
template is defined.