date_date_views_fields in core/modules/date/date.module

Implements hook_date_views_fields().

date_sql_handler::sql_field in core/modules/date/views/date_sql_handler.inc

Helper function to create cross-database SQL dates.

date_type_format in core/includes/date.inc

Helper function for getting the format string for a date type.

date_views_argument_handler_simple::init in core/modules/date/views/date_views_argument_handler_simple.inc

Get granularity.

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.

_date_views_fields in core/modules/date/views/date_views_fields.inc

Identify all potential date/timestamp fields.