Firefox makes use of external XML entities for localization by referring
<!ENTITY % whateverDTD SYSTEM "chrome://global/locale/whatever.dtd" >
Unfortunately, It does not load anything other than chrome: protocol
It does not even recognize W3C standard reference document here:
As a reference Google Chrome perfectly load external entities from the
Why can a bug live eleven years open without a fix and implementation?
Bug 22942 - (entities) Load external DTDs (entity/entities) (local and
remote) if a pref is set
In this case because the module owner feels that we should not be
implementing this functionality, no?