[tcs-lc] policy for relationships in TCS

[Kennedy, Jessie]

Dear All,

   Following recent discussions we had about relationships within taxon concepts and assertion relationships concerning one or more taxon concepts we thought it would be useful to clarify this aspect of the TCS structure in case it wasn't clear to everyone. It especially concerns the practice of establishing concept 
relationships. We intend to place this convention into the developing 
TCS documentation and user manual.

   As you know the TCS allows taxonomic experts to express relationships 
between concepts in two distinct places: (1) as an integral part of the 
TaxonConcept structure, and (2) separate from TaxonConcepts under 
RelationshipAssertions. Sometimes the latter are called 
"Third-Party-Relationships."

   If an expert asserts relationships between two concepts that were 
both authored at an earlier time, then by default these assessments are 
allocated to place (2), i.e. outside the TaxonConcepts section. Example: 
Brachycerinae sec. Kuschel (1995)  >  Brachycerinae sec. Marvaldi & 
Morrone (2000), asserted according to Franz (2005; the external third 
party).

   The TCS allows more choices if an expert simultaneously authors 
concepts AND asserts concept relationships. In that case, he or she has 
the option of placing the relationships inside the newly authored 
TaxonConcepts OR outside in the RelationshipAssertions.

   We recommend the former solution (1) if the author wishes to make the 
relationship to another concept an integral part of the new concept 
definiton. Note that we are not necessarily talking about parent-child 
relationships. Earlier, external concepts may be used as well to nail 
down the meaning of a newly published concept. Example: Ranunculus 
abortivus L. sec. Kartesz (2004)  = =  Ranunculus abortivus L. sec. FNA 
(1997), where Kartesz (2004) places this relationship into the 
TaxonConcept definition to indicate that the newly published 2004 
concept is defined (!) by its relationship to the FNA 1997 concept.

   We recommend the latter solution (2) if the author does not think of the 
relationship as an integral part of his or her new concept definition. 
Perhaps other data (diagnosis, included concepts, etc.) are sufficient 
to specify the present meaning. Or the relationship to earlier concepts 
is not so clear as to nail down the new definition exactly how the 
author wants it to be. Example: Equisetum hyemale L. ssp. affine 
(Engelmann) Calder & R.L. Taylor sec. Weakley (2005)  >  E. hyemale var. 
affine (Engelmann) A.A. Eaton sec. Radford, Ahles & Bell (1968), as 
asserted by Weakley (2005). Here the latter author does not wish to 
define his new concept via its (inclusive) relationship to the 1968 
concept. Rather, Weakley intends to provide readers with a "guide" to 
understanding the taxonomic legacy. The precise definition of his new 
concept lies in the diagnosis and explanatory comments.

   No matter what option an author chooses at the time of authoring a 
concept, the possibility of authoring another (now by default) 
third-party relationship at a later time remains. Such a reassessment 
would "coexist" with the earlier relationship. 

   We think that this convention of assigning concept relationships 
inside vs. outside of the TaxonConcepts section is sensible. It is 
something that experts will appreciate as guidance when defining 
concepts and their relationships.

With best wishes,


Nico, Jessie, Bob (Peet), Roger and Robert
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