Cultural Heritage markup can quickly become complex because of the need to represent multiple, and even overlapping, hierarchical structures. It can therefore become very difficult to maintain correctly.
This talk suggests that a better approach is now possible: markup that is designed to represent different aspects of a text could be handled separately from the point of view of checking and maintenance, and then only combined into a single document when needed, e.g. for some kind of analysis. Advances in comparison and merge tools for XML make this a possibility.