To use a single element to support your bilingual application, you declare a language element in the DTD (called language for this example). This language element would have an attribute for each of the two languages being supported in your bilingual application. The language element would be contained in a parent element with the content model (language+). This makes at least one language element mandatory, and more than one allowed, in the container element.

The element structure for this method looks like this:

The title is the container element. In it are two language elements: each with the lang attribute set for one of the two supported languages.

This method can be problematic if you want to align the content of the elements side by side. There must always be two matching elements present: one for each language. The responsibility is either on your authors to ensure that both elements are present in all cases; or you could use ACL to ensure that there are always two language elements present in any context: one with the attribute set for one language, the other with the attribute set for the other language. A missing element or elements could cause the document's side-by-side structure to be out of synchronization.