Deduplication of the entries in the DTD used for the plots in InDetPhysValMonitoring.
The baseline DTD is externalized to
!ENTITYs for the ITK plots.
InDetPVMPlotDefITK.xml, and the new
InDetPVMPlotDefLRT.xml files use the external DTD
InDetPVMPlotDefITK.xml override the
!ENTITYs they need for their plots.
InDetPVMPlotDefLRT.xml does this in-situ, as it's a only a small variation from the Run2 plots.
InDetPVMPlotDefITK.xml does this through a second external DTD.
These changes maybe take you half-way to a proper conditional DTD or XHTML solution, If these change are merged, a full XHTML solution should be fairly easy to implement.