Re: [gdmxml] Representation

2002-08-18 Thread Stan Mitchell



Hello Robert,Thank you for sharing 
your insight regarding the REPRESENTATIONand SOURCE entities. I hope you 
don't mind if I ask a couple offollow up questions.***The first 
question is about the relationship between REPOSITORY 
andREPRESENTATION.The SOURCE data definition, on page 74 of the GDM 
spec, states"One SOURCE is found in zero to many REPOSITORYs 
(throughREPOSITORY-SOURCE)."To setup my question, let's say I have 
one SOURCE that I've viewedin three REPOSITORYs. As a table it might look 
like this(I've formatted the tables using a fixed-pitch font) 
...SOURCE   REPOSITORY-SOURCE  
REPOSITORYID Comment   
Source-ID   Repository-ID  ID    
Name3358   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 
...REPRESENTATIONSource-ID   Representation-Type-ID  
Medium    
Content3358    
JPEG   
microfilm  nara.jpg3358    
JPEG   
microfilm  fhl.jpg3358    
JPEG   
digitally  
hq.jpg   
enhanced   
CD-ROMMy question: How does a REPRESENTATION link back to 
theREPOSITORY to determine where the image came from?A 
different interpretation of the REPRESENTATION entity ishinted at in another 
section of the specification. In the discussionof the Evidence Submodel on 
page 28, it states "If there are multiplecopies of a SOURCE, break them out 
at the lower level of theSOURCE hierarchy, and draw the ASSERTION from that 
levelor lower."Does this mean that each REPRESENTATION corresponds 
toa 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 
ofthe 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 aboutwhat the "correct" interpretation should 
be.***This is my second question; it concerns the relationship 
betweenSOURCE and REPRESENTATION.Let's say I have a census source 
and it is recorded hierarchicallyusing this table (in reality, there would 
be many more SOURCEscorresponding to all of the CITATION-PARTs) 
...SOURCEID  Higher-Source-ID  
Subject-Date  Comments2405    
- 
1850  pub level 
data2406    
2405  
June 4, 1850  page level data2407    
2406  
- 
household data2408    
2407  
- 
individual dataIf the REPRESENTATION is for a page of the census, would 
the Source-IDbe 2406? If I am using the REPRESENTATION as supporting 
evidence foran individual datum, say age at last birthday, could the 
Source-ID also 
be 2408? In table form, it would look like this ...
REPRESENTATIONSource-ID   Representation-Type-ID  
Medium    
Content2406    
JPEG    
microfilm 1850page.jpg2408    
JPEG    
microfilm 1850page.jpgIt 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 
textualREPRESENTATIONs to refer to the line and column items onthe 
census page. So instead, these REPRESENTATIONsmight be used 
...REPRESENTATIONSource-ID   Representation-Type-ID  
Medium    
Content2406    
JPEG    
microfilm 1850page.jpg2408    
TEXT    
microfilm "age, 45"The last REPRESENTATION appears to duplicate what 
isalso recorded in the CITATION-PARTs.My question: does a 
REPRESENTATION correspond to a particular(single) level in the SOURCE 
hierarchy and when is a REPRESENTATIONnot 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 MitchellGDMUML: 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 PMSubject: Re: [gdmxml] 
Representation> First, since I have not posted to this list 
before, let me introducemyself.> I am Robert Charles Anderson, one of 
the "Principal Membe

Re: [gdmxml] Representation

2002-08-16 Thread RCA

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



- Original Message -
From: Hans Fugal <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, August 15, 2002 10:41 PM
Subject: [gdmxml] Representation


> After about 5 weeks I'm finally getting back to this.  I hope everyone
> else's minds are less clouded over than my own. :)
>
> I have addressed all the elements of the evidence submodel to my liking
> with the exception of representation.  I have a few questions for the
> members of the LWG out there, as well as anyone who understands the
> representation and representation-type elements. (and anyone else, as
> well!)
>
> REPRESENTATION
> --
> source-id (FK)
> representation-type-id (FK)
> physical-file-code
> medium
> content (Text or multimedia)
> comments
>
> REPRESENTATION-TYPE
> ---
> representation-type-id (PK)
> representation-type-name
>
> My questions are:
> - First, what is a REPRESENTATION in the context of the GDM?
>   Specifically, how does it relate to a digital encoding and physical
>   representation? Is a photograph in my file cabinet a REPRESENTATION or
>   is that a SOURCE in and of itself? Or are representations only
>   encodings of the source that can be stored and transmitted? Most of
>   the rest of the questions stem from this one.
> - What is the difference between representation-type and medium?
> - Physical-file-code combined with a physical representation would seem
>   to be just another source that should be documented as such.
>
> And a few comments:
> - "One REPRESENTATION is a manifestation of one SOURCE" - so I will nest
>   representation in source in the xml format.
> - there are pre-existing standards for defining the location of things
>   in 'cyberspace' and the type and encoding of the data: URIs and
>   mime-types, respectively. I think it would be appropriate to bring
>   those into play if appropriate. One consideration in doing this of
>   course is that local URIs will only be valid on the local system (but
>   then so would any way of citing a file on the local system).
> - When content is a text transcription, it may be very appropriate to
>   use TEI for encoding the text.
> - When we wish to communicate an image or other binary format we could
>   mime-encode it just as we do with email attachments.
>
> 
> --
> "Everybody is talking about the weather but nobody does anything about
it."
> -- Mark Twain
>
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