How to reference to a other DTD in a DTD ?

[wxdqz]

Hi !I have a global DTD. This DTD is a representation of differents elementsthat are already defined in other DTD.The way is now define is that i had copied each DTD in myglobal DTD.The question i want to ask you : What's the best way toreference directly to each of my DTD ? This way you will notfind the same definition two times.I am knowing i can use entities but i am not sure that is the best solutionto what i want do to do. Can you say to me the best solution for me ?Thank you for help me !Beno顃 S関igny