note 126064 added to class.datetimeinterface

if you want to know what all the constants looks like, try <?php $constants= (new ReflectionClass("DateTimeInterface"))->getConstants(); foreach($constants as $name => $format){ echo "{$name}: " . date($format, 0) . "\n"; } ?> in php 8.0.3 it prints: ATOM: 1970-01-01T01:00:00+01:00 COOKIE: Thursday, 01-Jan-1970 01:00:00 CET ISO8601: 1970-01-01T01:00:00+0100 RFC822: Thu, 01 Jan 70 01:00:00 +0100 RFC850: Thursday, 01-Jan-70 01:00:00 CET RFC1036: Thu, 01 Jan 70 01:00:00 +0100 RFC1123: Thu, 01 Jan 1970 01:00:00 +0100 RFC7231: Thu, 01 Jan 1970 01:00:00 GMT RFC2822: Thu, 01 Jan 1970 01:00:00 +0100 RFC3339: 1970-01-01T01:00:00+01:00 RFC3339_EXTENDED: 1970-01-01T01:00:00.000+01:00 RSS: Thu, 01 Jan 1970 01:00:00 +0100 W3C: 1970-01-01T01:00:00+01:00 ---- Server IP: 45.112.84.4 Probable Submitter: 45.112.85.242 (proxied: 85.165.62.130) ---- Manual Page -- https://php.net/manual/en/class.datetimeinterface.php Edit -- https://main.php.net/note/edit/126064 Del: integrated -- https://main.php.net/note/delete/126064/integrated Del: useless -- https://main.php.net/note/delete/126064/useless Del: bad code -- https://main.php.net/note/delete/126064/bad+code Del: spam -- https://main.php.net/note/delete/126064/spam Del: non-english -- https://main.php.net/note/delete/126064/non-english Del: in docs -- https://main.php.net/note/delete/126064/in+docs Del: other reasons-- https://main.php.net/note/delete/126064 Reject -- https://main.php.net/note/reject/126064 Search -- https://main.php.net/manage/user-notes.php