Defines the format that date and time should be stored in. File core/modules/datetime/

datetime_date_default_time($date) Sets a consistent time on a date without time. The

Defines the format that dates should be stored in. File core/modules/datetime/

datetime_help($route_name, RouteMatchInterface $route_match) Implements

Defines the timezone that dates should be stored in. File core/modules/datetime/

Field hooks to implement a simple datetime field. File core/modules/datetime/datetime.module