Greetings,
I only just now subscribed to this list, and I apologize for not coming into the discussion earlier. I've just finished reading this complete thread in the archives, and I want to make a few comments while it's frseh in mind (as fresh as one's mind can be at 3:30am). I will expand (expound?) some more tomorrow.
I understand the desire to stick with familiar terms; but in the case of taxonomy, "familiar" can be a bad thing. Several critical words (e.g., "name", "concept", "taxon", etc.) mean slightly (sometimes not so slightly) different things to different people. As such, relying on the term itself to inform users of what the term represents (without referring them to the definition) can lead to disparate applications of the term in provided datasets. In my mind, it's better to use a less-familiar term that requires users to consult the definitoion, to reduce the chance of misapplication; rather than save the end user the trouble of consulting the definition by trying to use a familiar term that is definied differently by different people. Too much opportunity for a person to jump to the wrong conclusion about what content is expected in association with a particular term.
One of the biggest complaints I had about TCS 1.0 was the distinction between "name" and "concept". It was always my intent to try to suppress or eliminate this distinction in TCS 2.0; so I'm less eager than Stan is to cling to the terms as they exist in TCS 1.0.
Don't get me wrong -- I have been wrestling with data modelling of taxon names and taxon concepts since about 1990, so I am *VERY* familiar with what people mean when they distinguish names from concepts. But at an informatics level, I think Markus was absolutely right when he defined the "usage" as the most granular (and convenient) data object you can use to refer to either taxon concepts or taxon names. Our community has struggled with what to call this "thing" for a long time. Walter called it "Potential Taxon". I first started calling it "TaxonRef" (short for "Taxon Reference", based on pretty-much the same logic Dave Remsen alluded to). Then I started calling it "Assertion" (sensu: http://systbio.org/files/phyloinformatics/1.pdf). James Ytow had something similar called "Appearance"; but after years of conversations with him, we finally established that his "Appearance" was something slightly different (actually more granular). Others have called it a "Treatment" or "Taxon Treatment".
In developing GNUB, we finally settled on "TaxonNameUsage", because that was both explicit, and generic (and also wouldn't likely be confused with anything else in our field). Yes, it's cumbersome, but I think it represents the right balance of self-describing but without potentially disparate preconceived notions.
The definition is the usage or application of a taxon name within a particular documented context. "Documented context" is mostly published literature, but can also include any other forms of documentation, such as correspondence, unpublished manuscripts, single-copy documents such as field notes, specimen identification tags, etc. This is the core unit of information that GNUB will index and assign shared GUIDs to. I am absolutely convinced that it will become the standard currency for referencing taxon names and concepts.
The point that Markus was trying to make is that a TaxonNameUsage instance carries both an implied (or explicit) taxon concept circumscription, and also the nomenclatural metadata associated with how that circumcription was labelled (i.e., the "name"). This doesn't mean it's ambiguous, because it is what it is: a discrete Usage Instance. The difference is in what set of metadata is harvested from the identified Usage Instance. For example, consider:
1. Aus bus Smith 1950 sec Smith 1950 2. Aus bus Smith 1950 sec Jones 1960 3. Xus bus (Smith 1950) sec Brown 1970
We have one species epithet, and three TaxonNameUsage instances (TNUs). #1 is the original taxonomic description of the species "bus", which was originally combined with the genus "Aus". This has both a name part (Aus bus Smith 1950), and an implied taxon concept (sec Smith 1950). If I resolve any of these TNUs for nomenclatural information, I get a genus name, species epithet, an author, and a year. If I resolve them for taxon concept information, I get all the name bits plus the according to stuff ("sec" stuff); plus any other taxon concept information that is resolvable through that particular usage instance. Thus, whether you're interested in the nomenclature or the concept circumscription, you get both (explicitly) from referencing a TNU instance.
I'm too tired to write any more now, but I plan to expand on this tomorrow, with specific reference to the DwC terms and in the context of GNUB.
Aloha, Rich
Richard L. Pyle, PhD Database Coordinator for Natural Sciences and Associate Zoologist in Ichthyology Department of Natural Sciences, Bishop Museum 1525 Bernice St., Honolulu, HI 96817 Ph: (808)848-4115, Fax: (808)847-8252 email: deepreef@bishopmuseum.org http://hbs.bishopmuseum.org/staff/pylerichard.html