Taxonomic hierarchy

Gregor Hagedorn G.Hagedorn at BBA.DE
Wed Aug 27 12:39:39 CEST 2003

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 Hagedorn (G.Hagedorn at
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

Often wrong but never in doubt!

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