Implementing Taxonomic Identifications

Input

Every single taxon identification event generates a new record in the respective table. Complex identification are stored as a number of single identification events given by one and the same person on the same date referring to the same unit (e.g. a positive identification with one or more negative identifications "A non B nec C", or multiple modified identifications "cf. A vel aff. B"). The system has to ensure that only one positive unmodified identification event exists within a defined complex identification.

Handling of Similar Unit Sets

During data input, a preferred identification may be found to violate the name homogeneity rule within the SUS. In this case a dialogue with the user has to establish which of the following alternatives apply:

• The discrepancy is only the result of a nomenclatural change, which implies that no doubts exist about the taxonomic homogeneity of the SUS. It can be solved by setting all other preferred identification pointers for the units in the SUS to to the current unit.
• Alternatively the possibility exists that the SUS contains taxonomically different materials. This would be a violation of the definition of the SUS and the user must be alerted by the system to verify the homogeneity of the set. As a preliminary measure, a generated comment denotes the request to revise identification events and/or inheritance types in the SUS. Heterogeneous preferred identifications within the SUS are temporarily tolerated, to allow checking for misidentification or erroneous data input.

Output: Concatenation of an Identification String

The result of an single positive indentification is a taxon name string. However, for modified and complex identifications the following rules have to be applied:

• If a positive unmodified identification exists, it is always cited first.
• Positive identifications preceed negative ones.
• In the case of positive identification or confirmation the security of the identification may be expressed by a modifier (e.g. "cf." or "aff."), which is inserted in the taxon string at a position determined by the rank it refers to (e.g. cf. Abies alba, rank = genus, insertion preceeding genus name; Abies cf. alba, rank = species, insertion preceeding species epithet).
• In analogy to the citation of homonyms ( Greuter & al. 1994, recommendation 50C), the first negative identification following a positive identification should be preceeded by "non", all further negative identifications by "nec".
• In multiple modified identifications, the second and following taxon strings (including the modifier) are given in any sequence, each preceeded by "vel".

The complete identification string often cites the taxon string, followed by "det." and the identifier's name (and institutional afiliation), the date of the identification. Identifications attributed to a unit which in reality refer to another unit in the SUS may have to be indicated (eg. "dupl. det.").

No widely established citation type is currently used to denote identifications of the type "Absent", which we therefore refrain from treating here.

Implementation of Identification Events in the Berlin Botanical Garden Accession System

The datastructure used in the Berlin Botanical Garden Accession System does not implement the entire recursive unit structure proposed by CDEFD. However, identification events may apply to several interrelated components of the system, i.e. garden accessions, individual plants (parts of an accession), herbarium specimens collected in parallel to the accession, and garden herbarium specimens, taken from an individual in the garden (which in the past may have been specified only by an accession number). All these components are included in CDEFD's unit concept.

As a consequence, most of the problems formulated for the CDEFD-Model apply here as well. All components which are denoted by the same accession number should have the same scientific name. So the "accession set" is functionally analogous to the SUS in the CDEFD-Model.

For historical reasons, preferred identifications are marked by a flag in the identification event table. The system can store several identifications for any accession, individual plant, or herbarium specimen. However, for every accession set only one may be preferred. The system allows for (temporary) excemptions from this rule, it then generates a comment indicating that taxonomic homogeneity is not maintained, which is stored with all members of the set,.

The Berlin Botanic Garden Accession System is implemented in Microsoft Access. It currently undergoes beta testing and performance opmization. After completion, the program will be put in the public domain.