Index: wp-includes/time-constants.php
===================================================================
--- wp-includes/time-constants.php	(revision 0)
+++ wp-includes/time-constants.php	(revision 0)
@@ -0,0 +1,21 @@
+<?php
+/**
+ * Constants for expressing human-interval intervals in their
+ * respective number of seconds
+ */
+define( 'MINUTE_IN_SECONDS', 60 );
+define( 'HOUR_IN_SECONDS', 60 * MINUTE_IN_SECONDS );
+define( 'DAY_IN_SECONDS', 24 * HOUR_IN_SECONDS );
+define( 'WEEK_IN_SECONDS', 7 * DAY_IN_SECONDS );
+define( 'MONTH_IN_SECONDS', 30 * DAY_IN_SECONDS );
+define( 'YEAR_IN_SECONDS', 365 * DAY_IN_SECONDS );
+
+/**
+ * Constants for expressing human-interval intervals in their
+ * respective number of minutes
+ */
+define( 'HOUR_IN_MINUTES', 60 );
+define( 'DAY_IN_MINUTES', 24 * HOUR_IN_MINUTES );
+define( 'WEEK_IN_MINUTES', 7 * DAY_IN_MINUTES );
+define( 'MONTH_IN_MINUTES', 30 * DAY_IN_MINUTES );
+define( 'YEAR_IN_MINUTES', 365 * DAY_IN_MINUTES );