XML Editor :XML files can be edited in plain text in an editor program such as Vim, with all the code visible. There are also WYSIWYG XML editors that hide the code in the background and present the content to the user in a more user-friendly format, approximating the rendered version. This is helpful for situations where people who are not fluent in XML code need to enter information in XML based documents such as time sheets and expenditure reports.
From : en.wikipedia.org/wiki/XML_editor