The current XML representation of HDF5 dates back to the early days of XML, a time when XML tools were rather primitive and their support of XML-related standards patchy. This has left its mark on the first version of an HDF5 XML representation in that compromises had to be made between what standards governed and what fraction of features was available in tools and libraries across platforms. The situation has drastically improved over the last decade, new and revised standards have been published, and several new use cases have emerged. This might be the right time to review the present HDF5 XML representation and develop some ideas on how to overcome the "sins of the past."