Elements are objects derived from DhElement, which is the superclass of all user interface elements in the com.ms.wfc.html package. There is a certain consistency you can count on when using any object derived from DhElement:
If an element is already on the page when the DhDocument.onDocumentLoad method is called, you can call the document's findElement method and start programming to that element. You can also call setBoundElements from initForm to merge known elements on the page with elements in your DhDocument-derived class. (The findElement method has better performance but specifically requires that onDocumentLoad is called first.)
The searching routine used by findElement and setBoundElements assumes that the element you want to bind to has an ID attribute set to a particular name. Using findElement, you can also enumerate all the elements in the document until you find the one you are interested in.