Stan Mitchell
Sun, 18 Aug 2002 19:39:39 -0700
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Hello Robert,
Thank you for sharing your insight regarding the REPRESENTATION and SOURCE entities. I hope you don't mind if I ask a couple of follow up questions. *** The first question is about the relationship between REPOSITORY and REPRESENTATION. The SOURCE data definition, on page 74 of the GDM spec, states "One SOURCE is found in zero to many REPOSITORYs (through REPOSITORY-SOURCE)." To setup my question, let's say I have one SOURCE that I've viewed in three REPOSITORYs. As a table it might look like this (I've formatted the tables using a fixed-pitch font) ... SOURCE REPOSITORY-SOURCE REPOSITORY ID Comment Source-ID Repository-ID ID Name 3358 1850 Cens. 3358 2415 2415 NARA 3358 2617 2617 FHL 3358 2932 2932 HQ (HQ=HeritageQuest) The REPRESENTATION data definition, on page 67 of the spec, states "One SOURCE has zero to many REPRESENTATIONs." At each REPOSITORY, I've obtained a REPRESENTATION. So its table might look like this ... REPRESENTATION Source-ID Representation-Type-ID Medium Content 3358 JPEG microfilm nara.jpg 3358 JPEG microfilm fhl.jpg 3358 JPEG digitally hq.jpg enhanced CD-ROM My question: How does a REPRESENTATION link back to the REPOSITORY to determine where the image came from? ---- A different interpretation of the REPRESENTATION entity is hinted at in another section of the specification. In the discussion of the Evidence Submodel on page 28, it states "If there are multiple copies of a SOURCE, break them out at the lower level of the SOURCE hierarchy, and draw the ASSERTION from that level or lower." Does this mean that each REPRESENTATION corresponds to a unique SOURCE? That seems to contradict the data definitions. ---- There is another relationship to REPRESENTATIONs. In the data definition for REPOSITORY-SOURCE, on page 66 of the spec, it states, "Each instance in this entity represents a particular SOURCE in a specific
REPOSITORY." This implies that
each instance of REPRESENTATION will be
related to one instance
of REPOSITORY-SOURCE. This relationship is
not discussed in the
specification.
I'm hoping that you can clear up my confusion about what the "correct" interpretation should be. *** This is my second question; it concerns the relationship between SOURCE and REPRESENTATION. Let's say I have a census source and it is recorded hierarchically using this table (in reality, there would be many more SOURCEs corresponding to all of the CITATION-PARTs) ... SOURCE ID Higher-Source-ID Subject-Date Comments 2405 - 1850 pub level data 2406 2405 June 4, 1850 page level data 2407 2406 - household data 2408 2407 - individual data If the REPRESENTATION is for a page of the census, would the Source-ID be 2406? If I am using the REPRESENTATION as supporting evidence for an individual datum, say age at last birthday, could the Source-ID also be 2408? In table form, it would look like this ...
REPRESENTATION Source-ID Representation-Type-ID Medium Content 2406 JPEG microfilm 1850page.jpg 2408 JPEG microfilm 1850page.jpg It seems this would contradict the data definition on page 67 which states: "One REPRESENTATION is a manifestation of one SOURCE".
Here we have two SOURCEs to one REPRESENTATION (or image file).
Does this imply that I would need to create separate textual REPRESENTATIONs to refer to the line and column items on the census page. So instead, these REPRESENTATIONs might be used ... REPRESENTATION Source-ID Representation-Type-ID Medium Content 2406 JPEG microfilm 1850page.jpg 2408 TEXT microfilm "age, 45" The last REPRESENTATION appears to duplicate what is also recorded in the CITATION-PARTs. My question: does a REPRESENTATION correspond to a particular (single) level in the SOURCE hierarchy and when is a REPRESENTATION not a CITATION-PART? --- I hope my questions don't appear as hair-splitting.
I'm trying to create a faithful UML representation of GDM
and not introduce too much of my own interpretation.
Stan Mitchell GDMUML: http://freepages.tech.rootsweb.com/~mitchellsharp/ ----- Original Message ----- From: "RCA" <[EMAIL PROTECTED]> To: "Hans Fugal" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, August 16, 2002 5:59 PM Subject: Re: [gdmxml] Representation > First, since I have not posted to this list before, let me introduce myself. > I am Robert Charles Anderson, one of the "Principal Members" of the Lexicon > Working Group. Everybody in the LWG had both genealogical and technological > skills, in my case weighted more toward the former than the latter, although > I did learn a great deal about data modelling during the four years the > group worked together. > > I'll try to answer the first of Hans's questions, and maybe that will > clarify some of the later questions as well. As an example, let us say we > are working with a recorded deed, in a situation where the original deed > does not survive, or at least we don't know where it is. Then the recorded > deed is the SOURCE. If I create a written (paper) abstract of that deed, > then that is one REPRESENTATION. Then perhaps I go back to the courthouse > with my digital camera and take a photograph of that same deed, and now I > have a second REPRESENTATION. And then I make a complete transcript, as a > Word document, of the deed, and now I have a third. > > All three of these might end up in electronic form, but the abstract is > still a paper document, and could have a Physical-File-Code. A photographic > copy of the deed, not in digital form, would be another REPRESENTATION of > the same SOURCE, and could also have a Physical-File-Code. > > A second example of this would be a photograph of the family picnic on July > 4th of 1902, which your grandmother gave you when you were young. This > would be the SOURCE in this instance. A restored version of the photo would > be a REPRESENTATION, as would a digitized and stored version. > > To answer two of the sub-parts of your first question: > > "a photograph in my file cabinet" may be a SOURCE or a REPRESENTATION > depending on its pedigree. > > REPRESENTATIONs are not "only encodings of the source that can be stored and > transmitted" electronically. > > Hope this helps. > > RCA |