Joel,

As far as the release of the DwC RDF guide for public comment, I'm not intending to release it until there is consensus support (to the extent that I can figure out what that means) from the Task Group. So I definitely would not release it if you and other core members of the Task Group did not feel that it was ready. I have been working toward a June 30 deadline primarily because if people don't have deadlines, they usually don't take action and because I won't have much time to work on the project after August 1.

A technical point about your point (i.) below. As far as I can tell, all of the RDF for Darwin Core is now coming from the Google Code site rather than directly from rd.tdwg.org . John Wieczorek could confirm that. So although the xsl issue is somewhat annoying and should be fixed, I think the raw RDF can be viewed pretty easily by browsing in the http://code.google.com/p/darwincore/source/browse/#svn%2Ftrunk%2Frdf directory (if people know to look there). I can never remember how to get there, but there are links to the raw DwC RDF in section 0.3.7 of the Beginner's Guide (http://code.google.com/p/tdwg-rdf/wiki/Beginners ) as well as the source RDF of many other vocabularies.

As far as item (ii) is concerned, I'm willing to go with the consensus of the group. My main concern is "who will do it?". There are many things that should be done to improve the navigation and readability of the general TDWG Website but although that issue often gets discussed, no action has thus far been taken. The Darwin Core documentation is comparatively easy to navigate but it has the problem that it technically can't be changed without making a change to the standard itself. So I'm not sure where something served by tdwg.org would go without it just getting lost among the obsolete material in the maze of the TDWG Website. It might be logical to put a document such as you suggest on the DwC Google Code site (http://code.google.com/p/darwincore/), which I think is the default location for ancillary information about Darwin Core that isn't actually part of the standard.

You note that "There is no example of representing a Darwin Core occurrence in RDF!" The DwC RDF guide is intentionally written to be devoid of detailed implementation examples because of the problem that you have identified: the lack of a consensus data model/ontology for expressing biodiversity class relationships as RDF. The guide tries to follow the example of the non-RDF parts of Darwin Core, which is to provide terms and tell people how to use them without explicitly specifying their ranges or domains. I also have tried to avoid including anything that is likely to have to change much over time because if the Guide becomes part of the DwC Standard (alongside the Text and XML Guides) it can't be easily changed. However, I intend that the ancillary information (not part of the actual standard) will provide a variety of actual implementation examples. Those haven't all been written yet, partly because I didn't want to have to redo them if approaches suggested by the Guide itself didn't fly with the Task Group. However, I just finished a preserved specimen example using Darwin-SW this morning (http://code.google.com/p/tdwg-rdf/wiki/DwcRdfExamplesDarwinSW ) which hasn't been proofread carefully yet. I will try to give a shot at marking up the same metadata using taxonconcept.org object properties if I can and hopefully Rob and John Deck will provide an example of how they would serve metadata using the BiSciCol object properties. These examples can evolve and be added to as experimentation and experience guides us. But by keeping them out of the standard itself, they can do that freely without requiring the invocation of an official change to the standard. If at some point there is a consensus data model (or models), they could be formalized as TDWG Technical Standard that could sit on top of the basic DwC RDF guidelines. But my feeling is that it isn't necessary to wait for that model to complete the basic RDF Guide. I would be really happy to have a consensus or clarification about dwc:/dwctype:Occurrence. But I don't think the RDF Guide depends on that.

Others may wish to weigh in on this. Steve

joel sachs wrote:

This is an open letter to Steve Baskauf.

<context> For those who don't know, Steve came to TDWG a few years ago for answers on how to share data about plants, and and data about images of plants. He was, at the time, supplying three aggregators with data, and had to format his data differently for each one. Each of the aggregators had, in theory, embraced the semantic web, as had TDWG. So he started, in 2009, to ask some innocuous questions on the TDWG-content list regarding how to use TDWG standards. These questions led to such a cacophony of answers that he realized that TDWG needed help, and he agreed, in 2011, to co-convene the TDWG RDF-Task group, under the sponsorship of the TDWG TAG.

He shares the vision, espoused by many, that it would be better to build a "semantic layer" on top of Darwin Core, than to have to rebuild a "semantic Darwin Core" from scratch. The reason for this is that everyone has different semantic web needs, and, if forced to start from scratch, will build different semantic Darwin Cores. Then BCO and Darwin-SW and DWC-FP and Pyle/Whiton will have no way of understanding each other, while if they shared a basic underlying vocabulary [1], there would at least be a chance for data interoperability.

</context>

<email to Steve> Steve,

I proposed a moratorium on additions to Darwin Core until some fundamental things are cleaned up. I'm only aware of two additions pending: the addition of MaterialSample and MaterialSampleID to the "dwctype:" namespace; and the Darwin Core RDF guide, still receiving feedback from the task group. I do think that the MaterialSample proposal would be better framed atop a clearer semantics of existing terms and usage patterns, but who knows. I trust the proposers of the new terms to make good choices.

My current proposal (below) follows Guralnick's advice to narrow scope. It is partly motivated by the fact that you made a perfectly reasonable plea for clarification regarding the meaning of "occurrence", and no one is responding. (Yes, you only made the plea three days ago, but you've made many versions of it in the past.) In my opinion, it is unreasonable to expect the RDF Task Group to produce a guide for expressing Darwin Core in RDF unless some effort is made to clarify the semantics of a few Darwin Core terms.

So my current, less radical, proposal is this:

<proposal> That the RDF Task Group not release the draft guide for public comment until we (i.e. TDWG) improve the documentation around dwc:Occurrence and dwctype:Occurrence. By "improve", I mean:

i. Configure the rs.tdwg.org server to set an xml mime type for http://rs.tdwg.org/dwc/rdf/human-dwctype.xsl and http://rs.tdwg.org/dwc/rdf/human.xsl . (Currently the mime type is set to "text/plain", which results in users being unable to view either the raw RDF or the human-readable RDF in a standard browser.)

ii. In a single document, served by tdwg.org, list the valid usages/interpretations of dwc:Occurrence and dwctype:Occurrence. (I believe there are six.) Currently, to be aware of the various semantics of "Occurrence", a person needs to read half a dozen or so different documents. That's not necessarily bad, but there should at least be a "Guide to Standard 450", that links to and briefly explains the contents and purposes of each document.

</proposal>

Is that too much to ask of ourselves?

Now, you might say, "Fine, we should do that, but I'm not delaying release of the guide, which has already taken way too long to produce." And if you say that, I'll support you. But if we go ahead and release the guide without fixing some basic underlying things, I don't think it will have the impact that it should, for several reasons. Here's one of them:

<Example of how we're limiting ourselves> The draft guide is excellent. For many examples of what people want to do, the guide essentially creates a matrix with the dimensions "technical approaches" and "conceptual approaches", and proceeds to fill in every cell of this matrix with a valid usage pattern. It is meticulous. Yet there is a significant omission. There is no example of representing a Darwin Core occurrence in RDF! In the guide's defence, there is no way to do this without making significant assumptions about just what a Darwin Core occurrence is. </Example of how we're limiting ourselves>

Anyway, those are my thoughts, and some of my arguments. I will defer to your judgement on the best way to proceed.

Best, Joel.

</email to Steve>

1. Notice I said "vocabulary" and not "ontology". The less ontology

there is in the shared Core, the easier it will be for people to build on it to suit their needs. But a lack of ontology does not imply a lack of semantics. For proof, look at a dictionary - it has the complete semantics of the language. Similarly, Darwin Core - a "bag of terms", i.e. a glossary - is a perfect candidate to be a shared base layer for the semantic web … once it clarifies a few basic things.