creationdate format

Why does creationdate (13.1) mandate use of ISO8601 format instead of RFC
1123 which is the prefered date/time format for HTTP 1.1, as stated in RFC
2068, section 3.3.1

Also, can someone provide an example of an ISO 8601 format?  The RFC 1123
example from HTTP 1.1 is "Sun, 06 Nov 1994 08:49:37 GMT".  

Received on Tuesday, 16 December 1997 17:11:12 UTC