Hi,

I was also getting many stimulating ideas and questions after reading the ARK paper from California Digital Library last week and came up with the following Wiki page trying to capture some of my thoughts [http://wiki.gbif.org/guidwiki/wikka.php?wakka=GermplasmDatProviders].

I am not (yet) so worried if more than one GUID resolve to the same object. There might be conflicting views on what objects are duplicates and legitimate arguments to assign distinct identities to objects considered dupplictes by others. As in Sally example on specimen 'Chapman 541' at Kew beeing different from the specimen in Canberra in the view of the holding institutes. Both specimns originate from the same collecting event and share the same original source. I think there will actually be conflicting opinions if they are duplicates or not from for example a conservationist view. The conservationist could say "We want to conserve the natural diversity not any artificial diversity introduced during the act of conservation". I believe the collecting events and the physical specimens are different levels of units. Similar to how a specimen unit is not the complete truth of the taxon unit it is assigned to; if saying so makes sense? We are in fact planning a global database/index hosted in Rome, IPGRI these days on the germplasm collecting events. We hope the worldwide institutes with specimens from the same collecting event would consider to reference this event as a unique unit distinct from the specimen itself. Having a GUID and a resolving mechanism on both the event and the specimens would of cource be helpful.

A quick thought about Donalds coment on:

If identifier I1 refers to data object O1 and identifier I2 refers to data object O2, our minimal requirement for GUIDs would be that:

A) I1 == I2 --> O1 == O2 (for all relevant purposes)

We need to decide under which circumstances we want this to be a bidirectional implication, i.e. that:

B) O1 == O2 --> I1 == I2

I was wondering on the same last week and as refelected on the wiki page I mentioned above. Would it be acceptable to the GUID model to provide more than one metadata statement on the same object (GUID). A simple cache index which only mirror the metadata would not intend to improve or change the metadata, differences only from update frequency (old index). But resolving the GUID to the index/portal (as well as the original data provider if available) might be preferable to the original data source for performance and persistence reasons? But what if another indexing portal modify the metadata to correct or add missing values. This can be georeferencing or similar efforts. I think I would like my specimen GUID to resolve to this extra information, but also to keep it separate from the metadata "officially" provided. So should this additional improved metadata be assigned a new GUID? Sorry if this is a stupid question, but I have been wondering about this question this week.

What I am trying to get to is that there is a hierarchy of objects. The specimens belong to a taxon, belong to an original collecting event, belong to a holding institute... Metadata belong to an object, but should metadata sometimes be assigned its own GUID? I believe I am talking of metadata here and not digital objects on its own?

Dag Terje

Quoting Sally Hinchcliffe S.Hinchcliffe@kew.org:

Arthur wrote

...

To some extent I think Sally is right, what she suggests wouldn't

improve things with respect to duplicate specimens however- specimens of the same collection sent to more than one (and some times many) different institutions.

...

regarding duplicates, to my mind, there's a very strong connection between the duplicate of 'Chapman 541' held at Kew and the one held at Canberra (assuming there is such a thing). But they aren't the same thing (and shouldn't have the same id) - a photograph of Kew's duplicate would look nothing like a photograph of Canberra's duplicate for example. I'm not sure whether GUIDs are going to help us solve the problem of duplicates although I agree that it's desirable. What _could_ have the same GUID is the collecting event (Chapman taking a specimen) that gave rise to the two specimens ... but who or what would issue or control _those_ GUIDs?

Sally *** Sally Hinchcliffe *** Computer section, Royal Botanic Gardens, Kew *** tel: +44 (0)20 8332 5708 *** S.Hinchcliffe@rbgkew.org.uk