Editing XML (section)

=== Sources ===
XML is a profile of an ISO standard, SGML, and most of XML comes from SGML unchanged. From SGML comes the separation of logical and physical structures (elements and entities), the availability of grammar-based validation (DTDs), the separation of data and metadata (elements and attributes), mixed content, the separation of processing from representation ([[processing instruction]]s), and the default angle-bracket syntax. The SGML declaration was removed; thus, XML has a fixed delimiter set and adopts [[Unicode]] as the document [[Character encoding|character set]].

Other sources of technology for XML were the [[Text Encoding Initiative|TEI]] (Text Encoding Initiative), which defined a profile of SGML for use as a "transfer syntax" and [[HTML]]. The ERCS (Extended Reference Concrete Syntax) project of the SPREAD (Standardization Project Regarding East Asian Documents) project of the ISO-related China/Japan/Korea Document Processing expert group was the basis of XML 1.0's naming rules; SPREAD also introduced hexadecimal numeric character references and the concept of references to make available all Unicode characters. To support ERCS, XML and HTML better, the SGML standard IS 8879 was revised in 1996 and 1998 with WebSGML Adaptations.

Ideas that developed during discussion that are novel in XML included the algorithm for encoding detection and the encoding header, the processing instruction target, the xml:space attribute, and the new close delimiter for empty-element tags. The notion of well-formedness as opposed to validity (which enables parsing without a schema) was first formalized in XML, although it had been implemented successfully in the Electronic Book Technology "Dynatext" software;<ref>{{cite conference|first=Jon|last=Bosak|authorlink=Jon Bosak|url=http://2006.xmlconference.org/proceedings/162/presentation.html|archive-url=https://web.archive.org/web/20070711133314/http://2006.xmlconference.org/proceedings/162/presentation.html|archive-date=2007-07-11|title=Closing Keynote |conference=XML 2006 |date=12 July 2006|access-date=31 July 2009}}</ref> the software from the University of Waterloo New Oxford English Dictionary Project; the RISP LISP SGML text processor at Uniscope, Tokyo; the US Army Missile Command IADS hypertext system; Mentor Graphics Context; Interleaf and Xerox Publishing System.