From: Kevin Thiele kevin.thiele@PI.CSIRO.AU To: TDWG-SDD@USOBI.ORG
I think part of the basic problem [with DELTA] is that it's tried to force too much structure and while this is a great promise it's been an impediment in practice.
This is the problem with (or the virtue of) all character-based data systems (although DELTA does alleviate it by allowing comments and text 'characters', as discussed previously). I agree with Kevin that it is an impediment to acceptance of such systems. In fact, I think it's the main impediment - producing comparative data is difficult. Nevertheless, shouldn't this be one of the main objectives of taxonomy?
Thirty years ago, Leslie Watson wrote:
Perusal of the average taxonomic-descriptive work usually reveals that _as a source of comparative data_ it is hopeless. One genus will be described in terms of criteria that receive no mention in the next. Even species of the same genus may be described inconsistently. It is often impossible to distinguish with any degree of conviction between actual observation and extrapolation, between absence of a feature and mere failure to seek or comment on it. In general, the further one proceeds up the hierarchy, the less comparative the descriptions become. Given the situation prevailing in individual publications it is not surprising that scanning across them is even less satisfactory. ... If facts are wanted for reviewing the classification of a large group it is singularly disheartening to have to seek them in miscellaneous works of this kind. The labour is immense; worse, one sets out with the depressing knowledge that much of it will be wasted on discovering that the details thus compiled are not comparative. There is a welter of such material theoretically applicable to most major taxonomic problems, which will probably never be called upon because of its unpromising presentation and sheer intractability.
L. Watson (1971). Basic taxonomic data: the need for organisation over presentation and accumulation. Taxon 20, 131-136.
Things haven't improved much since, and they won't if we back away from teaching and strongly encouraging people to produce comparative data. Marking up free text into related chunks and making it available in electronic form would certainly reduce some of the labour, referred to above, of the person who is searching for comparative data. But it would not make non-comparative data comparative, and doing the markup would be a difficult and probably thankless task.
I think that, in addition to the classificatory problems alluded to above, the majority of nomenclatural problems (proliferation of synonyms) are the result of not having readily accessible, comparative data.
It seems to me that the main limitation of DELTA isn't simply ... that it's not complex enough.
I'd say that that's exactly the problem - for 'not complex enough', read 'doesn't have enough features'. Of course, to add new features in the best way, and to minimize the complexity in some sense, you might have to abandon existing data structures. However, we should not throw the baby out with the bathwater. That is, we should retain the useful features of current systems.
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Mike Dallwitz
CSIRO Entomology, GPO Box 1700, Canberra ACT 2601, Australia Phone: +61 2 6246 4075 Fax: +61 2 6246 4000 Email: md@ento.csiro.au Internet: biodiversity.uno.edu/delta/