You can define templates for custom display of your fields;
templates are available for: the event summary, the Event
Entry form, Event Popup windows, and the List View "details"
column. (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.