This was the role that XSL tried to fill but it never caught on. Part of the reason is that it's still very dependent on what information is in the source document; if it's not there you can't lay it out, and if you don't need it then it was a big waste of database time. This ends up reversing the dependency, so the contents of your "pure information" layer end up depending on what your "layout" layer needs, and in the end the difference between the layers is only nominal.