[tdwg-content] Delimiters for Darwin Core list-type terms

John Wieczorek tuco at berkeley.edu
Mon Oct 7 12:28:44 CEST 2013


Dear all,

On the list of pending Darwin Core issues is a topic of general
concern about terms that could or do recommend the concatenation and
delimiting of a list of values. The specific issue was submitted on
the Darwin Core Project site at
https://code.google.com/p/darwincore/issues/detail?id=168. Right now
there is variation in the recommendations of distinct terms.

The Darwin Core terms that could be used to hold lists include the
following (use the index at
http://rs.tdwg.org/dwc/terms/index.htm#theterms to find and see the
details of each of these):

informationWithheld
dataGeneralizations
dynamicProperties
recordedBy
preparations
otherCatalogNumbers
previousIdentifications
associatedMedia
associatedReferences
associatedOccurrences
associatedSequences
associatedTaxa
higherGeography
georeferenceSources
typeStatus
higherClassification
vernacularName

There are some issues. Many terms do not show examples. Most of those
that do show examples recommend semi-colon (';') -
associatedOccurrences, recordedBy, preparations, otherCatalogNumbers,
previousIdentifications, higherGeography, georeferenceSources, and
higherClassification, The example for higherClassification does not
have spaces after the semi-colon while all others do.

Terms that could hold a list of URLs would require a delimiter that
would be an invalid part of a URL unless it was escaped. This
precludes comma (','), semi-colon (';'), and colon (':'), among
others. One possibility here might be the vertical bar or "pipe"
('|').

The term dynamicProperties is meant to take key-value pairs. The
examples suggest the format key=value, with any list delimited by a
semi-colon, for example, "tragusLengthInMeters=0.014;
weightInGrams=120". The example for associatedTaxa also shows a
key-value pair ("host: Quercus alba"), but it is formatted differently
from the examples for dynamicProperties. There are other terms, such
as vernacularName, which could potentially also take a key-value pair,
though it is not currently recommended to be a list.

Please ignore the issue of whether the idea of list-type terms is a
good idea or not - that is not the issue we're trying to resolve here.
Instead, the issue is whether a consistent recommendation can be made
for how to delimit the values in a list. And if not a consistent
recommendation, can we make specific recommendations for distinct
terms? If specific recommendations can be made for a term, should that
be reflected in examples within the term definitions, or should such
recommendations reside only in Type 3 supplementary documentation such
as that which can be found on the Darwin Core Project site at, for
example, https://code.google.com/p/darwincore/wiki/Occurrence#associatedSequences?
Should some of these terms have specific recommendations to contain
only single values (e.g., vernacularName), in which case they are not
really viable in Simple Darwin Core?

Cheers,

John


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