The Jabber protocols have long included a method for indicating that a message or presence stanza was delayed in being delivered (e.g., because it was stored offline). This method makes use of the 'jabber:x:delay' namespace and has been documented variously in Internet-Drafts and elsewhere. Because this protocol is not required by &rfc2779;, the 'jabber:x:delay' namespace was removed from &xmppim;. This specification fills the void for canonical documentation.

The 'jabber:x:delay' namespace is used to provide timestamp information about data stored for later delivery. The most common uses of this namespace are to stamp:

• A message that is sent to an offline entity and stored for later delivery.
• The last presence update sent by a connected node to a host.
• Messages cached by a multi-user chat room for delivery to new participants when they join the room.

Information about the delivery delay is communicated by adding to the <message/> or <presence/> stanza one and only one <x/> child qualified by the 'jabber:x:delay' namespace. This information is added by the server or component that delivers the information. The following attributes are allowed on the <x/> element:

• from -- The Jabber ID of the entity that originally sent the XML stanza or that delayed the delivery of the stanza (for example, the address of a multi-user chat room). This attribute is RECOMMENDED.
• stamp -- The time when the XML stanza was originally sent. The format SHOULD be "CCYYMMDDThh:mm:ss" (see A Note on Time Formats below). This attribute is REQUIRED.

In addition, the <x/> element MAY contain XML character data that provides a natural-language description of the reason for the delay.

&xep0082; defines the lexical representation of dates, times, and datetimes in Jabber protocols. Unfortunately, the 'jabber:x:delay' namespace predates that definition, and uses a datetime format ("CCYYMMDDThh:mm:ss") that is inconsistent with XEP-0082 and &w3xmlschema2;. Because a large base of deployed software uses the old format, this document specifies that applications using 'jabber:x:delay' SHOULD use the old format, not the format defined in XEP-0082. The timezone is be understood as UTC.

Data qualified by the 'jabber:x:delay' can expose information about the sender's presence on the network at some time in the past. However, this introduces no new vulnerabilities, since the same information would have been available in real time.

This document requires no interaction with &IANA;.

The 'jabber:x:delay' namespace is included in the protocol namespaces registry maintained by the ®ISTRAR;.