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4.1. XHTML design considerations

It is all very well and good to say that CSS will handle the formatting of the taxonomic headings on the index page, but there is a subtle design problem that must be addressed.

In practice, all my work with bird classification has used the same set of taxonomic ranks: order, family, subfamily, genus, species, and subspecific form. To display taxa as an outline, we could just leave the order lines unindented; indent family lines one increment; indent subfamily lines two increments; and so on.

However, technically, in the underlying system for representing bird taxonomy, one can select a different set of ranks.

So the question is how much flexibility to build into the Web design to accommodate different sets of ranks. Also, where should this flexibility reside? To put the latter question differently, what software must change when the set taxonomic ranks changes?

The author's preference is to place the dependency in the CSS stylesheet. The XHTML generation step can tag the taxonomic heading lines with the rank code (e.g., “-f” for subfamily), so the logic that generates the XHTML does not have to be changed when the rank set changes. If the CSS gets out of synch with the rank set, the worst that can happen is the heading won't be formatted correctly; it will, however, still appear. This decision, in the author's opinion, minimizes the impact of using a different rank set.