A few years later, also in support of SGML Renaer, Mylonas and Durand presented a famous paper entitled ‘Refining our Notion of What Text Really Is: The Problem of Overlapping Hierarchies’ at Christ Church College, Oxford in 1992. Their ‘thesis’ stated that text is an ‘Ordered Hierarchy of Content Objects’, or ‘OHCO’ for short. In OHCO the ‘ordering’ comes from the fact that texts are linear: the objects of which they are composed succeed one another, and the objects themselves are hierarchical because structures like chapters, paragraphs, sentences and prose quotations ‘nest inside one another like Chinese boxes’. The key argument that lies behind the thesis, however, appears to be flawed: ‘if you treat texts as ordered hierarchies of content objets many practical advantages follow, but not otherwise. Therefore texts are ordered hierarchies of content objects.’ All this says about texts is that hierarchical structures are easily processed by computer. This follows in any case from the hierarchical nature of computable formal languages, but is also implied by Church’s model of computation from 1936: if all calculation can be modelled on recursion it follows that hierarchically organized data will be readily computable.