[XXE] How to convert docbook 5 documents to pdf

[Abu-Bakr Mostafa Taha]

HiI am starting to use XXE?3.5 professional edition. When I open a docbook?5 
file, the convert sub menudisappears. So how can I convert my docbook?5 file to 
pdf?Many thanks in advance;Dr. Abu-Bakr?M. tahaComputer Science Department, 
Qatar UniversityDoha, Qatar