Identifiers in PBCore (and a new person to the group)

[thompease]

Hi everyone. My name is Thom Pease, and I'm here representing the Music Library Association's interests in PBCore. I'm at the Library of Congress in the Recorded Sound Section and have worked in public radio in the past as a librarian. I'm becoming re-acquainted with the schema and hope you may be patient and helpful with me as I ask questions. I work mainly with AACR2/RDA/MARC data, and a little bit with other archival standards, so my questions will likely be from the perspective of mapping into and from PBCore for music and AV special collections' PB content.

My first questions are about identifiers. I see that there is pbcoreIdentifier which can "be used to reference or identify the entire record of a metadata descriptions for a media item" and instantiationIdentifier which “employs an unambiguous reference or identifier for a particular rendition/installation of a media item.” Is the common understanding that the first is for the intellectual content of the asset, and the second for particular instantiations (i.e. tapes, files, etc.) that can be located on a shelf or as particular files? If so, are both recursive on the level of [intellectual content] parts and instantiation parts? Can an instantiation refer to multiple Description documents? If so, I see this as a useful thing, as we have many compilation tapes which contain various bits of contents on a tape. We also have tapes which have different instantiation characteristics such as speeds, configurations—is that able to be described in pbCore?

Lastly, there is instantationRelationIdentifier. I’m unclear to as to what values may go here. There seems to be no vocabulary or examples. How would this element be used? Is it meant to exemplify a relationship type from an external vocabulary? Thanks again and I look forward to working with you all.

[kvanmalssen]

Hi Thom,

Welcome and thanks for your interest in PBCore!

To attempt to answer your questions:

Is the common understanding that the first is for the intellectual content of the asset, and the second for particular instantiations (i.e. tapes, files, etc.) that can be located on a shelf or as particular files?

Yes, that is correct. There is a repeatable element for content identifiers, and another for instantiation or carrier identifiers.

If so, are both recursive on the level of [intellectual content] parts and instantiation parts? Can an instantiation refer to multiple Description documents?

Yes, and vice versa. You may have a content item that spans multiple instantiations, or an instantiation that has multiple content items.

If so, I see this as a useful thing, as we have many compilation tapes which contain various bits of contents on a tape.

This is very common in public media collections as well.

We also have tapes which have different instantiation characteristics such as speeds, configurations—is that able to be described in pbCore?

Yes, this is the reason for having multiple instantiations related to one intellectual content item. The model allows you to describe the various manifestations of a particular content item, e.g. a 1/4" reel, a CD, and a WAV file, all that contain the same content. Each of these has it's own technical characteristics (speed, etc), which can be described using the instantiation elements.

Regarding instantiationRelationIdentifier - this would be to express the identifier of a related instantiation (in the Dublin Core sense of related). I agree that there is some confusion about how this should be used, and little guidance. We are currently working on improving the definitions and guidelines for various elements. I'll hold off on trying to give an example or improved definition here, since the review is currently underway.