RE: Saving markup formats

[Drew Adams]

Interesting post, Oliver. Lots of food for thought. Thanks.

> I'd start designing the data structure. I would do it with an eye on
> the various specifications for XML (most notably: the XML info set and
> the style properties in CSS)

What about the XQuery and XPath data model (XDM), instead of the Infoset? It's 
essentially the XML Infoset + XML Schema types. From the W3C XDM spec 
(http://www.w3.org/TR/xpath-datamodel/): 

 The data model is based on the [Infoset] (henceforth "Infoset"),
 but it requires the following new features to meet the [XPath
 2.0 Requirements] and [XML Query Requirements]:

 * Support for XML Schema types. The XML Schema recommendations
   define features, such as structures ([Schema Part 1]) and
   simple data types ([Schema Part 2]), that extend the XML
   Information Set with precise type information.

 * Representation of collections of documents and of complex values.
   ([XML Query Requirements])

 * Support for typed atomic values.

 * Support for ordered, heterogeneous sequences.