问题
What is the difference between XML 1.0 and XML 2.0?
回答1:
There has never been an XML 2.0, even as a draft.
There is a not entirely popular XML 1.1 standard which has three main changes, the most important of which was somewhat controversially applied in-place to XML 1.0 in XML 1.0 5th edition.
It changes the set of allowed element and attribute names (essentially XML 1.0 had a fixed set of names and new characters added to Unicode were not allowed in names; XML 1.1 changed that to an open set such that all currently unallocated code points to be used in names). This change applies to XML 1.0 5th edition as well as XML 1.1.
XML 1.1 changed the white space characters treating the IBM NEL terminator U+2028 as an end of line character. It changed the rules around control characters allowing them (apart from code point 0) into XML encoded as numeric character references, so  is legal XML 1.1 but not XML 1.0.
回答2:
Nowhere XML 2.0 , but some proposals for what XML 2.0 might look like:
- elimination of DTDs from syntax,
- integration of namespaces,
- XML Base and XML Information Set (infoset) into the base standard
Search term XML 2.0 on wikipedia page.
There are no much discussions on XML 2.0 , though, I found this little informative.
来源：https://stackoverflow.com/questions/17038605/difference-between-xml-1-0-and-xml-2-0