entity declaration

[Ramin Raybod]

Hi, I'm an xml amateur reader. I have a problem. If I want to have an entity in a document,is it really need to define a DTD for it including the doc elements structure? Suppose u have a large doc and full of complex elements and u r not required to use a DTD for it but you want to have a recurring entity. Is it possible not to define the whole dtd and have just your favorite entity :) thanx Ramin