Eric Gouda wrote:

I'm highly interested in a DELTA like format that is XML based (done a lot with XML lately) to provide hirarchical features in the items part.

This is a part we have purposely excluded in the discussions in Brazil and Paris so far, and perhaps it is time to open a discussion about this on the list. The answer to this discussion looms in the background of the current SDD outline, since it may cause major structural rearrangments. I therefore believe it important that we deal with it.

The reason for not taking on the object hierarchy of the described items is that it has two aspects:

1. Fundamental evolutionary hierarchy = taxonomic systematics -> in my opinion it is not the purpose of a descriptive data standard to cover this. The hierarchisation of taxa into an evolutionary tree is a complex and contentious process that is independent of the fundamental data that are being observed (rather than implied by the taxonomic hierarchy) -> just like taxon concepts, obligate and facultative synonymy, the the hierarchisation of taxa should be covered by a separate taxonomic standard. -> to produce complete Flora/Fauna treatments, these standards need to work together. -> Note that a new TDWG "Taxonomic Names" xml standards group has been formed. The convener is Jerry Cooper and it will meet the first time at the TDWG meeting in Portugal

2. However, several aspects of complex descriptive data sets need an operational access to a taxonomic hierarchy. -> default values for new items -> observations assumed to be true for an entire group but not actually observed should be noted as "higher taxa" descriptions and the information should be treated as implied in lower taxa. The situation is identical for implying information from species to subspecies as it is from Family to species. -> Note that in contrast to DELTA, SDD has no special "subspecies mechanism" -> scoping characters in/out for specific groups. Scoping means that characters are only applicable or desirable to code only in certain groups (in contrast to character dependency, which is a reflexive relationship within descriptive data)

(What other data or features depend on the taxon hierarchy? Can anybody provide good discussion examples?)

So, I have no good solution for this. One option would be to simply allow any operational hierarchization in SDD and not care about taxonomic codes, standards, etc. at all, only providing a linking mechanism to taxonomic data sets. Is that desirable?

Gregor ---------------------------------------------------------- Gregor Hagedorn (G.Hagedorn@bba.de) Institute for Plant Virology, Microbiology, and Biosafety Federal Research Center for Agriculture and Forestry (BBA) Koenigin-Luise-Str. 19 Tel: +49-30-8304-2220 14195 Berlin, Germany Fax: +49-30-8304-2203

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