Taxonomic hierarchy in SDD

Robert A. (Bob) Morris ram at CS.UMB.EDU
Tue Nov 27 18:31:06 CET 2001

Here's another need for Use Cases. Oops. I mean data challenges.
I suspect it is not profitable to approach this problem without
detailed examples. Those examples might illuminate whether the
problems of hierarchy rearangement can simply be handled by XSLT, as
probably can the examples you give.

Bob Morris

Eric Zurcher writes:
 > Date:         Wed, 28 Nov 2001 09:54:06 +1100
 > From: Eric Zurcher <Eric.Zurcher at>
 > To: TDWG-SDD at
 > Subject:      Re: Taxonomic hierarchy in SDD
 > One additional point to consider is that hierarchies arise not only in the
 > classification of items (taxa or specimens), but also in the classification
 > of the characters used to describe those item. And along both the item and
 > character "axes", there will often be multiple, alternative hierarchies
 > which reflect different purposes or philosophies.
 > For example, in assembling an interactive key to plants, one might well
 > want to group characters dealing with leaves separately from characters
 > dealing with the infloresence. And perhaps a trickier "hierarchy" of
 > characters is one that might be used to describe the rules for "natural
 > language" generation, aggregating characters into phrases, sentences and
 > paragraphs.
 > Does anyone see a good generalized mechanism for handling the creation and
 > maintenance of hierarchies (or other groupings)?
 > Here are a few thoughts off the top of my head: Because of the need for
 > handling alternative hierarchies for different purposes, it would seem
 > logical to keep the "classification" separate from the "core" data (going
 > back to DELTA, this was one reason why "directives" files were used - it
 > provided a mechanism for changing groupings without touching the core
 > data). But this approach comes at a significant cost: if the "core" data is
 > changed, it will probably require synchronized changes in the various
 > hierarchy descriptions which reference that data. Maintaining consistency
 > becomes a problem. Perhaps the way out is to make use of unique global
 > identifiers (GUIDs), as Steve Shattuck has suggested.
 > At 10:43 PM 26-11-01 -0500, Bob Morris wrote:
 > >We may not be arguing here. I don't dispute the need for this, only
 > >argue that there should not be a standard for taxonomy, but rather a
 > >standard for how to specify taxonomy. Or any other hierarchy for that
 > >matter.
 > >
 > >Doing this would allow you to get the hiearchy from /any/ suitable
 > >source, including but not limited to the data source itself. To me it
 > >seems that the least brittle thing for data inheritance is to use the
 > >same model as for datatype inheritance, i.e. a separate "schema" to
 > >which reference is made, as Tim Jones argued.
 > Eric Zurcher
 > CSIRO Livestock Industries
 > Canberra, ACT Australia
 > E-mail: Eric.Zurcher at

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