Remote elements are elements that are not fully contained in the MPD document but are referenced

18 in the MPD with an HTTP-URL using a simplified profile of XLink.

19 A remote element has two attributes, @xlink:href and @xlink:actuate. @xlink:href

20 contains the URL for the complete element, while @xlink:actuate specifies the resolution

21 model. The value "onLoad" requires immediate resolution at MPD parse time, while "onRe-

22 quest" allows deferred resolution at a time when an XML parser accesses the remote element.

Resolution (a.k.a. dereferencing) consists of two steps. Firstly, a DASH client issues an HTTP

4 GET request to the URL contained in the @xlink:href, attribute of the in-MPD element, and

5 the XLink resolver responds with a remote element entity in the response content. In case of error

6 response or syntactically invalid remote element entity, the @xlink:href and

7 @xlink:actuate attributes the client shall remove the in-MPD element.

8 If the value of the @xlink:href attribute is urn:mpeg:dash:resolve-to-zero:2013,

9 HTTP GET request is not issued, and the in-MPD element shall be removed from the MPD. This

10 special case is used when a remote element can be accessed (and resolved) only once during the

11 time at which a given version of MPD is valid.

12 If a syntactically valid remote element entity was

Period specifies the information of a Period.

@xlink:href O specifies a reference to a remote element entity that is either empty or contains one or multiple top-level elements of type Period

@xlink:actuate OD default: onRequest specifies the processing instructions, which can be either "onLoad" or "onRequest". This attribute shall not be present if the @xlink:href attribute is not present.

[gml] adopted the [xlink11] standard to represent links between resources. At the time of adoption, XLink was the only W3C-endorsed standard mechanism for describing links between resources within XML documents. The Open Geospatial Consortium anticipated broad adoption of XLink over time - and, with that adoption, provision of support within software tooling. While XML Schema, XPath, XSLT and XQuery etc. have seen good software support over the years, this never happened with XLink. The authors of GML note that given the lack of widespread support, use of Xlink within GML provided no significant advantage over and above use a bespoke mechanism tailored to the needs of GML.

[GML] adopted the [XLINK11] standard to represent links between resources. At the time of adoption, XLink was the only W3C-endorsed standard mechanism for describing links between resources within XML documents. The Open Geospatial Consortium anticipated broad adoption of XLink over time - and, with that adoption, provision of support within software tooling. While XML Schema, XPath, XSLT and XQuery etc. have seen good software support over the years, this never happened with XLink. The authors of GML note that given the lack of widespread support, use of Xlink within GML provided no significant advantage over and above use a bespoke mechanism tailored to the needs of GML.

New Version Available: XLink 1.1 (Document Status Update, 14 September 2010)

The XML Core Working Group has produced a W3C Recommendation for a new version of XLink which adds features to this 2001 version while remaining compatible. Please see XLink 1.1 for the latest version.

ID – This attribute is used to link internally and to reference an element from outside the instance.

xlink – This attribute is used for an external link. It is defined in the as xlink:simpleLink, (see information about the XML Linking Language ), which in the XML schema specification has a further breakdown for different types of xlinks. At this time, only xlink:href is envisioned in MODS records.

<abstract xlink:href= "http://www.ojp.usdoj.gov/bjs/abstract/cchrie98.htm"/>