Editing XML (section)

== Overview ==
The main purpose of XML is [[serialization]], i.e. storing, transmitting, and reconstructing arbitrary data. For two disparate systems to exchange information, they need to agree upon a file format. XML standardizes this process. It is therefore analogous to a [[lingua franca]] for representing information.{{sfnp|Dykes|2005|p=1}}

As a [[markup language]], XML labels, categorizes, and structurally organizes information.{{sfnp|Dykes|2005|p=11}} XML tags represent the data structure and contain [[metadata]]. What is within the tags is data, encoded in the way the XML standard specifies.{{sfnp|Dykes|2005|p=11}} An additional [[XML schema]] (XSD) defines the necessary metadata for interpreting and validating XML. (This is also referred to as the canonical schema.){{sfnp|Dykes|2005|p=135}} An XML document that adheres to basic XML rules is "well-formed"; one that adheres to its schema is "valid".{{sfnp|Dykes|2005|p=135}}

{{anchor|Media types}}[[History of the Internet#Internet Engineering Task Force|IETF]] [[:RFC:7303|RFC 7303]] (which supersedes the older [[:RFC:3023|RFC 3023]]), provides rules for the construction of [[media type]]s for use in XML message. It defines three media types: <code>application/xml</code> (<code>text/xml</code> is an alias), <code>application/xml-external-parsed-entity</code> (<code>text/xml-external-parsed-entity</code> is an alias) and <code>application/xml-dtd</code>. They are used for transmitting raw XML files without exposing their internal [[semantics]]. RFC 7303 further recommends that XML-based languages be given media types ending in <code>+xml</code>, for example, <code>image/svg+xml</code> for [[SVG]].

Further guidelines for the use of XML in a networked context appear in [[:RFC:3470|RFC 3470]], also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language.<ref name="WhatIs" />