Current XMLtext field type uses the old xmltext ezxml format, a better approach in the future would be to use and update the Document component so it handles the internal format instead (docbook).
The Field Type may expose several formats like intended with eZ Document Component, but for WYSIWYG editors and web use there is a need to have a xhtml5 like format that has all the capabilities of ezxml or even more.
A xhtml5 wysiwyg format could be based on ezxml but with some changes:
- Tag names should be changed to names in html5, most are easy, custom tag is not.
- Tags should behave as in html5 (inline / block / inline-block), and custom tags should be able to be one of these.
- Attribute names should be aligned with html5 (map custom attribute to -data-?)
- Valid parent and child tags might need some minor adjustments, table in paragraphs for instance.
- As for section tags, that can be mapped to the html5 section tag, and this can be visually hinted by the editor in needed: http://www.tinymce.com/tryit/html5_formats.php
For Legacy Database there could be a converter that transforms the format to ezxml, if eZ Document Component is used then it needs some updates for minor changes done to the format in 4.1.