Identification for alternate renditions

The OCF 1.0 specification, in point 2.3.2, gives a way to provide multiple renditions of a single publication. However, there appears to be no way to identify these multiple renditions other than by media-type. A publication, might, for instance, include several PDF versions, with different font sizes, or margins, or faces, or illustrations... but, if a reading system were to let the user choose between these PDF versions (I don't think any current reading system does), there would be no way for the user to know which is which.

I suggest an optional "title" attribute or similar should be allowed for the <rootfile> element or, if this is already implicit from the different spec inheritances, it should be made clear in the OCF spec, and shown in the examples.