Document content type interfaces.
$Id: Document.py 37023 2005-05-26 15:27:36Z yuppie $
Textual content, in one of several formats.
Get the "raw" (as edited) form of the text.
Get the "cooked" (ready for presentation) form of the text.
Updatable form of IDocument.
Update the document.
safety_belt, if passed, must match the value issued when the edit
began.