CodeLens is supported for .dtd files, which can show where an element declaration is referenced.
This feature also supports listing and highlighting the number of references to an element declaration and the line(s) referenced on.
See CodeLens for more details.
After defining an !ELEMENT tag in the .dtd file, there are features available for categories.
For an !ELEMENT tag that contains a category/element-content attribute, there is support for navigating to its definition element.
DTD syntax validation is enabled for any .dtd file.
