1. A document structure for representing a document being interchanged among document processing systems comprising: one or more nestable segments for representing components of the document, more than one level of nesting being permitted in a segment and the segments being so ordered that a segment representing a component dependent from a given component is always nested within the segment representing the given component, each segment having one of a plurality of types and containing (1) means for identifying the start and type of the segment at the beginning of the segment; (2) means for representing the contents of the segment; and (3) means for identifying the end and type of the segment at the end of the segment.
1. A document structure for representing a document being interchanged among document processing systems comprising: one or more nestable segments for representing components of the document, more than one level of nesting being permitted in a segment and the segments being so ordered that a segment representing a component dependent from a given component is always nested within the segment representing the given component, each segment having one of a plurality of types and containing (1) means for identifying the start and type of the segment at the beginning of the segment; (2) means for representing the contents of the segment; and (3) means for identifying the end and type of the segment at the end of the segment. 4. In the document structure of claim 1 and wherein: the means for representing the contents of the segment contains at least one descriptor containing information about the segment.