posted 15 years ago
XSD and DTD are two different ways of defining rules that an xml instance should follow.
These rules tell things like what should be the root element, how many times an element should appear and what is the data type of the same, etc.
This helps to render some predictability to the otherwise unpredictable xml.
What i mean by above is, by definition xml only guarantees well formedness and not any rule as to what elements can appear in the xml. So, it is very difficult for a consumer of the xml to determine what elements he is going to get and hence processing becomes a pain. XSD/DTD acts as an agreement saying, this is how the xml will look like!
