Not limited to the structure of a document, it addresses the complete range of visual presentation issueshow a document looks. It is an entire framework for representing, in a complete manner, both the structure and the visual presentation of the various elements that make up the structure. If a document is encoded using ODA, and you give it to another ODA site, you can expect it to look exactly the same when printed at the other site. Just as clearly, that is the reason why the standard itself ,and the implementations of ODA, have been slower to come into existence. ODA refers to document structure in two fundamental ways.
Documents have a logical structure and a layout structure.
The layout structure, however, refers to the positioning of elements as objects to be placed on paper. This layout structure divides a document into page sets, pages, frames, and blocks to describe the way information is to be placed on paper. The connection between the logical and layout structures is made via a layout directive. Next the relationship of the logical and layout structures for this simple business letter are illustrated. This makes a good deal of intuitive sense.