Needed to detect incompatible changes between versions of these files (see bug #40724 comment #1).
Metrics files for TYPE0 and TRUETYPE fonts now have a metrics-version attribute: <font-metrics metrics-version="2" type="TYPE0"> and the FontReader throws a SAXException when reading those files, if the version info is absent or incompatible.
batch transition pre-FOP1.0 resolved+fixed bugs to closed+fixed