If you compare WordML with other markup languages serving formatters as input format, as is the case, for example, for XSL-FO, especially the different structures stand out.
Whereas XSL-FO knows recursions and often uses them in praxis, they are unknown in WordML. Recursions serve two concepts which have proved successful in XML layout structures. On the one hand, an inheritance is made possible. One example are inline HTML elements which can be nested. The following tags would generate an underlined text in italics:
<i> <u> in italics and underlined </u> </i>
By using this principle, entire text passages can be marked with an element and they can be re-formatted differently.
On the other hand, the number of required elements can be reduced since, for example, no element is needed which generates an italicized and underlined text at the same time.
Whereas, as already explained, WordML does not know this way of inheritance. All formatting properties are parts of paragraph styles, inline styles or of direct formatting. The inheritance between these three formatting possibilities exists in the way that by direct formatting inline styles can be overwritten and these, in turn, can overwrite paragraph styles in case formatting properties which are contradictory confront each other.
These differences in the inheritance and aspects like the very unconventional line structure and the flat structure of WordML are very significant because they explain why Microsoft has decided for this structure and breaks with the unwritten principles of XML layout structures.
It is likely that WordML is an implementation of the previous saving format "doc" in XML. Since Word had been developed when procedural programming was popular and aspects like inheritance did certainly not play a role, it seems likely that the encrypted saving format "doc" has also been tailored to these requirements.
Despite the unconventional concept of WordML, one cannot but consider WordML as a progress. The scenarios introduced in the application part of the book would not be possible in such an extent without WordML.
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