Section 3.1.4.2 says that the filterNotValid exception applies to properties filter. Why is it here (and only here) applied to the renditionFilter (assuming that is what is intended, the text is unclear). If this exception applies to only properties, then it should not be overloaded for this service. If it applies to both rendition and property filters, then it should be that way for all the other services which also accept a renditionFilter.