date_default_value in core/modules/date/date.elements.inc
The callback for setting a default value for an empty date field.
date_default_value_part in core/modules/date/date.elements.inc
Helper function for the date default value callback to set either 'value' or 'value2' to its default value.
date_field_load in core/modules/date/date.field.inc
Implements hook_field_load().
date_field_presave in core/modules/date/date.field.inc
Implements hook_field_insert().
date_field_widget_form in core/modules/date/date.field.inc
Implementation of hook_field_widget_form().
date_formatter_process in core/modules/date/date.module
Helper function for creating formatted date arrays from a formatter.
date_views_argument_handler::get_query_fields in core/modules/date/views/date_views_argument_handler.inc
Collect information about our fields we will need to create the right query.
date_views_argument_handler_simple::init in core/modules/date/views/date_views_argument_handler_simple.inc
Get granularity.
date_views_filter_handler::get_query_fields in core/modules/date/views/date_views_filter_handler.inc
date_views_filter_handler_simple::init in core/modules/date/views/date_views_filter_handler_simple.inc
Provide some extra help to get the operator/value easier to use.