- They are not written in XML syntax, which means you have to learn a new syntax in order to write them
- there is no support for namespaces
- there are no constraints imposed on the kind of character data allowed, so datatyping is not possible
- there is minimal support for code modularity and none for inheritance
- large DTDs are hard to read and maintain
- there are no default values for elements and attribute defaults must be specified when they are declared
- its attribute value models and ID attribute mechanism are simplistic
- there is limited ability to control whitespace
- there is limited documentation support, as you cannot use the structured documentation features available for schema notation
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Filed under: XML
