Abstract: A style of document format known as compound document architecture is known, in which a document is broken up into a tree of objects or segments (e.g. document: chapter: subtitle: para: para: etc.), possible with a second layout tree. Two styles of such architecture are ODA and CDA. Conversion from CDA to ODA presents difficulties, as in CDA, a segment can contain e.g. text and graphic elements, while ODA has stricter formatting rules. One of a plurality of DAPs (Document Application Profiles) 12 is selected, depending on which subset of full ODA is being used. The DAP contains a structure converter component which starts to construct the objects of the ODA document. When an information element is reached (text, graphics, etc.), it is sent to the appropriate one of a set of content handlers 13. These call back to callback units (text, graphics, footnote, etc.