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XML in general
Where do I find general information about XML?
- http://www.w3schools.com/xml/default.asp - A host of information and hands-on examples
- http://en.wikipedia.org/wiki/XML - A good starting point
Is there only one kind of Moodle XML?
No, there are (at least) two different kinds of Moodle XML, one for importing/exporting glossaries and one for questions (quizzes), the latter being the one usually referred to as "Moodle XML".
Then there is XML in the SCORM/IMS packages that Moodle can import and must be able to handle. These packages are educational content that has been marked up in a special way to be able to be used in compatible Learning Management Systems.
The course backup and restore process also generates an XML file (inside the zip file) that contains all the information about the course.
Where do I find documentation about Moodle XML?
Are there tools for converting to and from Moodle XML?
- Microsoft Office macros: http://finemetronome.com/moodle/
- OpenOffice XML filters (TBA see  for some pointers)
- Online XML Converter - allow to create XML from text files
How can I view and edit XML files?
XML is just text so you can view and edit it with any text editor. However, this isn't very easy for anything more than a trivial file. There are a number of dedicated XML editors available for many platforms. If you only need to view the XML, most browsers are able to render XML files. Some even let you view the source text and do some basic editing.