[citation needed] Groupe μ categorized the figures of narration are following Hjelmslev's sign model, and included in the analysis of each group the perspective of two fundamental aspects of Quintilian's classical rhetoric: the principle of deviation from a norm,[2][3] and the four fundamental operations for such of variation.
[4][5][6] His analysis distinguished between expression-figurae (or figurae of the expression plane) and content-figurae,[4][6] and then within each between form and content.
They avoid discussion the figures of the substance of content, wondering if they are actually conceivable, and leave them to future works building a universal theory of semantics.
[7] For the figures of the substance of expression they make the examples of diction in speech and the font of a written text.
In printing a book, it is possible to choose among several fonts: in the final results, the physical medium and substance will be the same, they will just have different modalities.