There are obvious ways in which text and diagrams within a document should be coordinated: for instance, the placement of a diagram might influence the wording of the text. However, there is a more subtle interaction between text and diagrams, which has emerged from work on generating technical documents that make extensive use of layout. Constituents that would normally be classified as textual may contain diagrammatic features (e.g., when multiple indenting is used); conversely, non-pictorial diagrams usually contain short strings of text (e.g., labels within boxes). We argue that text and diagrams really lie on a continuum, and that for generating documents of this kind we need a descriptive framework that combines linguistic and graphical features in the same representation.