[XXE] XXE 2.2 Which DTD and how to convert

[Michel Kergoat]

Hello
I've installed XXE 2.1 std and began to write some docbook documents 
which are using DTD 4.1.2.
Now I've installed XXE 2.2 std and would like to use DTD 4.2 because it 
is more usefull.
How to convert my 4.1.2 documents to 4.2 ?
Which DTD is XXE using when I made file / new ?
Does it depend on the catalogs files ?
Thank you in advance
Michel:-)