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mapping.md

File metadata and controls

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Details of the METS + EAD → JSON mapping

METS

Our objects in ExploreUK, regardless of whether they have finding aids or not, are required to have a METS file.

For our purposes, the following sections are relevant:

dmdSec - descriptive metadata section

Our METS files usually have a single dmdSec for object-level metadata, which we record in Dublin Core. Example:

<mets:dmdSec ID="DMD1">
    <mets:mdWrap MDTYPE="OAI_DC" MIMETYPE="text/xml">
      <mets:xmlData>
        <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
          <dc:title xml:lang="en">James Edwin Weddle Photographic Collection</dc:title>
          <dc:source>James Edwin Weddle Photographic Collection</dc:source>
          <dc:creator>Weddle, James Edwin, 1911-1989</dc:creator>
          <dc:identifier>1997av027</dc:identifier>
          <dc:subject>Horse sports.</dc:subject>
          <dc:subject>Horse racing -- Kentucky -- Lexington -- Pictorial works</dc:subject>
          <dc:subject>Thoroughbred horse.</dc:subject>
          <dc:subject>Lexington (Race horse)</dc:subject>
          <dc:publisher>University of Kentucky</dc:publisher>
          <dc:date>1948-1981</dc:date>
          <dc:format>collections</dc:format>
          <dc:type>text</dc:type>
          <dc:language>English</dc:language>
          <dc:rights>Copyright to the collection is not held by University of Kentucky. Reproduction and usage permissions can be obtained from University of Kentucky for images not identified as material published by the  Associated Press, or United Press International. Permission to reproduce those images must be secured from the individual organizations. (Identifications or publication notices are noted in the individual item records.)  Contact the Special Collections Research Center for information regarding rights and use of this collection.</dc:rights>
          <dc:description>32 Cubic Feet 66 boxes (10946 items)</dc:description>
        </oai_dc:dc>
      </mets:xmlData>
    </mets:mdWrap>
  </mets:dmdSec>

In particular, the dc:source element is human-readable shared metadata for individual items within a collection.

fileSec - file section

We organize fileSec into a number of fileGrps. Files within a fileGrp are different manifestations of the same underlying object. Example:

<mets:fileGrp ID="FileGrp115">
  <mets:file ID="ThumbnailFilee32d581c82b0079697654b79be4347e9" USE="thumbnail" MIMETYPE="image/jpeg">
    <mets:FLocat xlink:href="1997av027/Box_2/Item_115/1997av027_0115_tb.jpg" LOCTYPE="OTHER"/>
  </mets:file>
  <mets:file ID="FrontThumbnailFile104dbe363f0e8f263dab0c52557b64ba" USE="front thumbnail" MIMETYPE="image/
jpeg">
    <mets:FLocat xlink:href="1997av027/Box_2/Item_115/1997av027_0115_ftb.jpg" LOCTYPE="OTHER"/>
  </mets:file>
  <mets:file ID="ReferenceImageFile991ff9a4b7d76b6f8dbee2d7746e58e2" USE="reference image" MIMETYPE="image/
jpeg">
    <mets:FLocat xlink:href="1997av027/Box_2/Item_115/1997av027_0115.jpg" LOCTYPE="OTHER"/>
  </mets:file>
  <mets:file ID="PrintImageFilef19cc4a2d47746ad4263e294ecaa80ae" USE="print image" MIMETYPE="application/pd
f">
    <mets:FLocat xlink:href="1997av027/Box_2/Item_115/1997av027_0115.pdf" LOCTYPE="OTHER"/>
  </mets:file>
</mets:fileGrp>

In this example, all four files represent digitized versions of the same physical artifact, with different uses (such as "thumbnail" or "reference image").

For collections with finding aids, there is a special fileGrp which references the EAD file or files associated with the collection.

<mets:fileGrp ID="FileGrpFindingAid" USE="Finding Aid">
  <mets:file ID="MasterFindingAid" MIMETYPE="application/xml" USE="master">
    <mets:FLocat LOCTYPE="OTHER" xlink:href="1997av027.xml"/>
  </mets:file>
  <mets:file ID="AccessFindingAid" MIMETYPE="application/xml" USE="access">
    <mets:FLocat LOCTYPE="OTHER" xlink:href="1997av027.dao.xml"/>
  </mets:file>
</mets:fileGrp>

This allows the EAD file, the encoded finding aid, to be discovered, given access to the METS file and its containing DIP.

structMap - structural link section

We use the structMap to document a logical reading order for digital objects. For finding aids, we use a two-level structure. The top level divides a collection into "sections", and the lower level serves as pagination within a section. Depending on how the collection is organized, sections may have a single "leaf" or many. Example:

<mets:div TYPE="section" LABEL="115" ORDER="115">
  <mets:div TYPE="photograph" LABEL="Animals; Cats; Close-up of kitten" ORDER="1">
    <mets:fptr FILEID="ThumbnailFilee32d581c82b0079697654b79be4347e9"/>
    <mets:fptr FILEID="FrontThumbnailFile104dbe363f0e8f263dab0c52557b64ba"/>
    <mets:fptr FILEID="ReferenceImageFile991ff9a4b7d76b6f8dbee2d7746e58e2"/>
    <mets:fptr FILEID="PrintImageFilef19cc4a2d47746ad4263e294ecaa80ae"/>
  </mets:div>
</mets:div>

The FILEID attribute in the fptr element matches the ID attribute of the corresponding file in the fileSec.

EAD

Our finding aid collections in ExploreUK generally have an EAD file. Content managers decide whether to process specific collections with or without EADs. The finding aid viewer and the METS + EAD → JSON converter only handle collections which have both METS and EAD.

As of April 2024, we continue to use the EAD 2002 standard.

JSON

This software reads a METS file, uses that to find the access copy of the EAD, then extracts metadata from both files, organizing them into a JSON object.

A skeletal JSON object

{
  "header": {
    "abstract": "...",
    "descriptive_summary": {
      "title": "...",
      "date": "...",
      "creator": "...",
      "extent": "...",
      "subjects": ["...", "..."],
      "arrangement": "...",
      "finding_aid_author": "...",
      "preferred_citation": "..."
    },
    "collection_overview": {
      "biography_history": "...",
      "scope_and_content": "...",
      "processing_info": "..."
    },
    "restrictions_on_access_and_use": {
      "conditions_governing_access": "...",
      "use_restrictions": "..."
    },
    "special_links": {
      "ead": "https://...",
      "more_from_this_collection": "https://..."
    }
  },
  "contents_of_the_collection": [
    /* described below */
  ]
}

contents_of_the_collection

The contents_of_the_collection field is an array of entries. Each entry corresponds to a component of the collection. Every entry should have at least the following fields:

  • id
  • level
  • title

In uncommon cases, an entry will also have the following fields:

  • biography_history
  • scope_and_content
  • title

A component in a collection can have subcomponents, and the value of the subcomponents field is an array of entries corresponding to those subcomponents, recursively.

A component can have one or more container lists. These are listed in the container_lists field. A container list should have the following fields:

  • id
  • summary
  • volume
  • container
  • container_list

If there is digitized content corresponding to a component, links to that content should be stored in the links field. Each entry in the links field can have one or more subentries, one for each manifestation of a file in the digitized object. Example:

"links": [
  [
    [
      {
        "id": "xt734t6f3d29_115_1_thumbnail",
        "use": "thumbnail",
        "mimetype": "image/jpeg",
        "href": "1997av027/Box_2/Item_115/1997av027_0115_tb.jpg"
      },
      {
        "id": "xt734t6f3d29_115_1_front_thumbnail",
        "use": "front thumbnail",
        "mimetype": "image/jpeg",
        "href": "1997av027/Box_2/Item_115/1997av027_0115_ftb.jpg"
      },
      {
        "id": "xt734t6f3d29_115_1_reference_image",
        "use": "reference image",
        "mimetype": "image/jpeg",
        "href": "1997av027/Box_2/Item_115/1997av027_0115.jpg"
      },
      {
        "id": "xt734t6f3d29_115_1_print_image",
        "use": "print image",
        "mimetype": "application/pdf",
        "href": "1997av027/Box_2/Item_115/1997av027_0115.pdf"
      }
    ]
  ]
]