Structural map section
The structural map section <structMap> provides a means for organizing the digital content represented by the <file> elements in the <fileSec> of the METS document into a coherent hierarchical structure. (Note, if there is any other structure that better suits your needs that is fine, but hierarchical structures are most prevalently used here.) Such a hierarchical structure can be presented to users to facilitate their comprehension and navigation of the digital content. It can further be applied to any purpose requiring an understanding of the structural relationship of the content files or parts of the content files. The organization may be specified to any level of granularity (intellectual and or physical) that is desired. The section may contain one or more structural maps, with using repeatable <structMap> element, which allows more than one structure to apply to the digital content represented by the METS document.
The structure provided by the <structMap> may be purely intellectual or logical (such as a book divided into chapters), purely physical (a book divided into sequences of pages), or a mixture of logical and physical (a book sub-divided into chapters and subsequently divided into a sequence of pages). The content organized by the <structMap> may include many mixtures of digital content files: structured or unstructured text, image, audio, video and/or application (such as pdf).
In addition to the content represented by the files in the <fileSec> of the same METS documents, the <structMap> may also encompass and organize content represented by integral, external METS documents. Thus, the <structMap> of a METS document representing a digital version of a journal series might organize the multiple external METS documents representing the individual issues of the journal in the order of publication. The <structMap>s of the METS documents representing the individual issues might then organize their content.
In addition to providing a means for organizing content, the <structMap> provides a mechanism for linking content at any hierarchical level with relevant metadata. For more on this type of linking see the section on the <div> element below.
The hierarchical structure specified by a <structMap> is encoded as a tree of nested <div> elements. A <div> element may directly point to content via child file pointer <fptr> elements (if the content is represented in the <fileSec> or child METS pointer <mptr> elements (if the content is represented by an external METS document). The <fptr> element may point to a single whole <file> element that manifests its parent <div>, or to part of a <file> that manifests its <div> It can also point to multiple files or parts of files that must be played/displayed either in sequence or in parallel to reveal its structural division. The <div>, <mptr>, <fptr>, and other <structMap> elements that make this sophisticated structuring possible are described in detail below.
The example encodings in this <structMap> section show a variety of possible ways of structuring a digital version of the Martial Epigrams, some more plausible than others. The main intent throughout is not to present definitive encodings, but rather just to demonstrate the variety and flexibility of the structural mechanisms offered by METS. The best structural choices for a particular work depends on a variety of factors: the nature of the work being digitized, the anticipated users of the digital version, the kind or kinds of presentation desired, the capabilities of the available presentation programs, etc.
Elements contained in the structural map section
Representing parts of a digital object: <div>
The structural divisions of the hierarchical organization provided by a <structMap> are represented by division <div> elements, which can be nested to any depth. Each <div> element can represent either an intellectual (logical) division or a physical division. It can explicitly identify the form of <div> it represents via its TYPE attribute. Thus in the case of a digitized book subdivided by the <structMap> into nested <div> elements representing chapters and then pages, the TYPE attribute values of the <div> elements at each successive level of the hierarchy might be “book”, “chapter”, and “page”.
The optional LABEL attribute value can identify a <div> element in a specific manner suitable for presentation to the user of the digital object. So, a hierarchical presentation of the <div> LABEL attribute values would typically form a kind of “table of contents” that digital library patrons could use to comprehend and navigate the content represented by a digital object encoded using METS. The LABEL attribute could, of course, serve different purposes in different applications of the METS standard.
<fileGrp> may point to pertinent metadata groups <mdGrp> and metadata elements <md> in the Metadata Section <mdSec> of the METS document by means of an MDID attribute.
A <div> element at any level can be associated with one or more metadata groups <mdGrp> and metadata elements <md> in the Metadata Section <mdSec> of the METS document by means of its MDID attribute. It is assumed that any metadata referenced by a <div> element pertains to the division as a whole. For example: the root <div> in a digital object encoded using METS that represents a video might point to a <md> element that expresses the copyright and access restriction information for the entire video.
Example
The simple encoding fragment below demonstrates the div features described thus far, including the TYPE, LABEL, and MDID attributes.
<?xml version="1.0" encoding="UTF-8"?>
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:mods="http://www.loc.gov/mods/v3"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd
http://www.loc.gov/mods/v3 http://www.loc.gov/mods/v3/mods-3-1.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams">
<mets:mdSec>
<mets:md ID="DMD1" USE="DESCRIPTIVE">
<mets:mdWrap MDTYPE="MODS">
<mets:xmlData>
<mods:mods>
<mods:titleInfo>
<mods:title>Martial Epigrams</mods:title>
</mods:titleInfo>
</mods:mods>
</mets:xmlData>
</mets:mdWrap>
</mets:md>
</mets:mdSec>
...
<mets:structSec>
<mets:structMap TYPE="physical">
<mets:div TYPE="book" LABEL="Martial Epigrams II" MDID="DMD1">
<mets:div TYPE="page" LABEL="Blank page"/>
<mets:div TYPE="page" LABEL="Page i: Series title page"/>
<mets:div TYPE="page" LABEL="Page ii: Blank page"/>
<mets:div TYPE="page" LABEL="Page iii: Title page"/>
<mets:div TYPE="page" LABEL="Page iv: Publication info"/>
<mets:div TYPE="page" LABEL="Page v: Table of contents"/>
<mets:div TYPE="page" LABEL="Page vi: Blank page"/>
<mets:div TYPE="page" LABEL="Page 1: Half title page"/>
<mets:div TYPE="page" LABEL="Page 2 (Latin)"/>
<mets:div TYPE="page" LABEL="Page 3 (English)"/>
<mets:div TYPE="page" LABEL="Page 4 (Latin)">
<mets:div TYPE="page" LABEL="Page 5 (English)"/>
<mets:div TYPE="page" LABEL="Page 6 (Latin)"/>
<mets:div TYPE="page" LABEL="Page 7 (English)"/>
</mets:div>
</mets:structMap>
</mets:structSec>
</mets:mets>
Through its subsidiary elements, each <div> element points to the digital content that manifests it. It can do so through one or more <mptr> element, if this content is represented by one or more external METS documents, or through one or more <fptr> element, if this content is represented by one or more <file> elements in the <fileSec> In addition to or instead of directly pointing to digital content via its child <fptr> and/or <mptr> elements, a <div> element may itself contain <div> elements that further subdivide the content represented by the division.
Connecting structure and content with file pointers: <fptr>
The <fptr> or file pointer element represents digital content that manifests its parent <div> element. The content represented by an <fptr> element must consist of integral files or parts of files that are represented by <file> elements in the <fileSec> Via its FILEID attribute, an <fptr> may point directly to a single integral <file> element that manifests a structural division. (See the section in Chapter 4 on internal linking above, and the description of the FILEID attribute in the attribute table for the <fptr> element below). However, an <fptr> element may also govern an <area> element, a <par> element, or a <seq> element which in turn would point to the relevant file or files. A child <area> element can point to part of a <file> that manifests a division, while the <par> and <seq> elements can point to multiple files or parts of files that together manifest a division. (For fuller information on the <area>, <par>, and <seq> elements see the dedicated sections below).
More than one <fptr> element can be associated with a <div> element. Typically sibling <fptr> elements represent alternative versions, or manifestations, of the same content. For example, a page of a manuscript might be represented by a thumbnail image, a reference image, a master image, and a structured text version of the page content. Each of these versions would be represented by a <file> element in the <fileSec> The <div> element in the <structMap> corresponding to this page of the manuscript would therefore have four child <fptr> elements, each of which points to one of the alternative versions of the content. Typically sibling <fptr> elements represent alternative versions, or manifestations, of the same content. Additional attributes associated with the <fptr> element include ID and CONTENTIDS. Descriptions of all of the attributes associated with the <fptr> element appear in the table below.
Example
The following METS encoding fragment represents a case where the <structMap> as a whole represents a purely physical structure. The root division represents the whole book, and each structural division under this root represents a physical page. Each page division has three associated content files, each of which represents a different image manifestation (TIFF, JPEG, or GIF) of the same content:
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams II">
...
<mets:fileSec>
<mets:fileGrp USE="MASTER IMAGE">
<mets:file ID="epi01m" MIMETYPE="image/tiff">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/full01.tif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi02m" MIMETYPE="image/tiff">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/full/02.tif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi03m" MIMETYPE="image/tiff">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/full/03.tif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi04m" MIMETYPE="image/tiff">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/full/04.tif"
LOCTYPE="URL"/>
</mets:file>
...
</mets:fileGrp>
<mets:fileGrp USE="REFERENCE IMAGE">
<mets:file ID="epi01r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/01.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi02r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/02.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi03r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/03.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi04r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/04.jpg"
LOCTYPE="URL"/>
</mets:file>
...
</mets:fileGrp>
<mets:fileGrp USE="THUMBNAIL IMAGE">
<mets:file ID="epi01t" MIMETYPE="image/gif">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/gif/01.gif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi02t" MIMETYPE="image/gif">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/gif/02.gif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi03t" MIMETYPE="image/gif">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/gif/03.gif"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi04t" MIMETYPE="image/gif">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/gif/04.gif"
LOCTYPE="URL"/>
</mets:file>
...
</mets:fileGrp>
</mets:fileSec>
<mets:structSec>
<mets:structMap TYPE="physical">
<mets:div TYPE="book" LABEL="Martial Epigrams II" MDID="DMD1">
<mets:div TYPE="page" LABEL="Blank page">
<mets:fptr FILEID="epi01m"/>
<mets:fptr FILEID="epi01r"/>
<mets:fptr FILEID="epi01t"/>
</mets:div>
<mets:div TYPE="page" LABEL="Page i: Half title page">
<mets:fptr FILEID="epi02m"/>
<mets:fptr FILEID="epi02r"/>
<mets:fptr FILEID="epi02t"/>
</mets:div>
<mets:div TYPE="page" LABEL="Page ii: Blank page">
<mets:fptr FILEID="epi03m"/>
<mets:fptr FILEID="epi03r"/>
<mets:fptr FILEID="epi03t"/>
</mets:div>
<mets:div TYPE="page" LABEL="Page iii: Title page">
<mets:fptr FILEID="epi04m"/>
<mets:fptr FILEID="epi04r"/>
<mets:fptr FILEID="epi04t"/>
</mets:div>
...
</mets:div>
</mets:structMap>
<mets:structSec>
</mets:mets>
Composing digital objects from multiple METS documents with METS pointers: <mptr>
Like the <fptr> element, the METS pointer <mptr> element represents digital content that manifests its parent <div> element. Unlike the <fptr>, which either directly or indirectly points to content represented in the <fileSec> of the parent METS document, the <mptr> element points to content represented by an external METS document. Thus, this element allows multiple discrete and separate METS documents to be organized at a higher level by a separate METS document. For example, METS documents representing the individual issues in the series of a journal could be grouped together and organized by a higher level METS document that represents the entire journal series. Each of the <div> elements in the <structMap> of the METS document representing the journal series would point to a METS document representing an issue. It would do so via a child <mptr> element. Thus the <mptr> element gives METS users considerable flexibility in managing the depth of the <structMap> hierarchy of individual METS documents.
The <mptr> element points to an external METS document by means of an LOCREF attribute as described in the section on external linking. (See Chapter 4). This is the same mechanism used for associating <file> elements with external content files in the FLocat element.
Example
The example below illustrates the application of the <mptr> element to the case of a book issued in two volumes, each of which is represented by a discrete METS document. Using the <mptr> element, the METS document below binds the two separate METS documents representing the individual volumes together into a single METS document representing the entire two-volume set.
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:mods="http://www.loc.gov/mods/v3"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd
http://www.loc.gov/mods/v3
http://www.loc.gov/mods/v3/mods-3-1.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams I & II">
<mets:mdSec>
<mets:md ID="DMD1" USE="DESCRIPTIVE">
<mets:mdWrap MDTYPE="MODS">
<mets:xmlData>
<mods:mods>
<mods:titleInfo>
<mods:title>Epigrams / Martial ; with an English translation by
Walter C.A. Ker</mods:title>
</mods:titleInfo>
<mods:physicalDescription>
<mods:extent>2 v. ; 17 cm</mods:extent>
</mods:physicalDescription>
</mods:mods>
</mets:xmlData>
</mets:mdWrap>
</mets:md>
</mets:mdSec>
...
<mets:structSec>
<mets:structMap TYPE="physical">
<mets:div TYPE="multivolume book" LABEL="Martial Epigrams I & II" MDID="DMD1">
<mets:div TYPE="volume" LABEL="Volume I">
<mets:mptr LOCTYPE="URL"
LOCREF="http://www.loc.gov/standards/mets/documentation MatrialEpigrams.xml"/>
</mets:div>
<mets:div TYPE="volume" LABEL="Volume II">
<mets:mptr LOCTYPE="URL"
LOCREF="http://www.loc.gov/standards/mets/documentation/MatialEpigramsII.xml"/>
</mets:div>
</mets:div>
</mets:structMap>
</mets:structSec>
</mets:mets>
Including parts of files in the structure: <area>
The area <area> element typically points to content consisting of just a portion or area of a file represented by a <file> element in the <fileSec> In some contexts, however, the <area> element can also point to content represented by an integral file.
A single <area> element would appear as the direct child of a <fptr> element when only a portion of a <file>, rather than an integral <file>, manifested the digital content represented by the <fptr> In this case the <area> element both identifies the pertinent <file> via its FILEID attribute and specifies the pertinent area of that file via its SHAPE and COORDS attributes (in the case of image content) or some combination of BETYPE, BEGIN, END, EXTTYPE and EXTENT attributes (in the case of text or audio /video content).
Multiple <area> elements would appear as the direct children of a <par> element or a <seq> element when multiple files or parts of files manifested the digital content represented by an <fptr> element. As described below, the <par> and <seq> elements are used to group multiple files or parts of files that must be played/displayed in parallel or in sequence to manifest the digital content represented by the parent <fptr> element. In these cases, each individual file, or file segment, would be represented by a child <area> element. When used as the direct child of an <fptr> element, as is described in the paragraph above, the <area> element typically points to just an area or segment of an integral file. When used in the context of a <par> or <seq> element, however, an area element can point either to an integral file or to a segment of a file as necessary.
Example
The example below demonstrates the use of the <area> element to isolate particular areas of the image files that are referenced in the associated FILEID attributes. It shows both uses of the <area> element as a direct child of an <fptr> element and as a direct child of a <seq> element. In the former case, the specified area of the referenced image manifests the parent division by itself. In the latter case, the specified areas of two different images must be displayed in sequence to fully manifest the parent division.
<?xml version="1.0" encoding="UTF-8"?>
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams">
<mets:fileSec>
<mets:fileGrp USE="REFERENCE IMAGE">
<mets:file ID="epi09r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/09.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi11r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/11.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi13r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpeg/13.jpg"
LOCTYPE="URL"/>
</mets:file>
</mets:fileGrp>
</mets:fileSec>
<mets:structSec>
<mets:structMap TYPE="logical">
<mets:div TYPE="volume" LABEL="Martial Epigrams II">
<mets:div TYPE="section" LABEL="Book VIII">
<mets:div TYPE="introduction" LABEL="Introduction: Latin">
<mets:fptr>
<mets:seq>
<mets:area FILEID="epi09r" SHAPE="RECT" COORDS="0,1150,2500,3150"/>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,600,2500,900"/>
</mets:seq>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram I: Latin">
<mets:fptr>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,1000,2500,1500"/>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram II: Latin">
<mets:fptr>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,1500,2500,2350"/>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram III: Latin">
<mets:fptr>
<mets:seq>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,2350,2500,3050"/>
<mets:area FILEID="epi13r" SHAPE="RECT" COORDS="0,500,2500,2100"/>
</mets:seq>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram IV: Latin">
<mets:fptr>
<mets:area FILEID="epi13r" SHAPE="RECT" COORDS="0,2100,2500,2700"/>
</mets:fptr>
</mets:div>
</mets:div>
</mets:div>
</mets:structMap>
<mets:structSec>
</mets:mets>
For further examples of how the <area> element can be used in the context of the <seq> and <par> elements, see the sections on these elements immediately below.
Presenting content sequentially: <seq>
The sequence of files <seq> element aggregates pointers to files, parts of files and/or parallel sets of files or parts of files that must be played or displayed sequentially to manifest a block of digital content. This might be the case, for example, if the parent <div> element represented a logical division, such as a diary entry, that spanned multiple pages of a diary and, hence, multiple page image files. In this case, a <seq> element would aggregate multiple, sequentially arranged <area> elements, each of which pointed to one of the image files that must be presented sequentially to manifest the entire diary entry. If the diary entry started in the middle of a page, then the first <area> element (representing the page on which the diary entry starts) might be further qualified, via its SHAPE and COORDS attributes, to specify the specific, pertinent area of the associated image file.
Example
The example below shows a case where a logical structuring of the digital content provided by the <structMap> is supported by the <seq> element. The structuring in this case is independent of the physical layout of the material in the analog source. The <structMap> here divides Book VIII of Martial’s Epigrams into Latin and English versions, each of which is manifested by the sequences of files comprising the version.
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams">
<mets:fileSec>
<mets:fileGrp USE="REFERENCE IMAGE">
<mets:file ID="epi09r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/09.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi10r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/pjg/10/jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi11r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/11.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi12r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/12.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi13r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/13.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi14r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/14.jpg"
LOCTYPE="URL"/>
</mets:file>
...
</mets:fileGrp>
</mets:fileSec>
<mets:structSec>
<mets:structMap TYPE="logical">
<mets:div TYPE="volume" LABEL="Martial Epigrams II">
<mets:div TYPE="section" LABEL="Book VIII">
<mets:div TYPE="subsection" LABEL="Latin version">
<mets:fptr>
<mets:seq>
<mets:area FILEID="epi09r"/>
<mets:area FILEID="epi11r"/>
<mets:area FILEID="epi13r"/>
...
</mets:seq>
</mets:fptr>
</mets:div>
<mets:div TYPE="subsection" LABEL="English version">
<mets:fptr>
<mets:seq>
<mets:area FILEID="epi10r"/>
<mets:area FILEID="epi12r"/>
<mets:area FILEID="epi14r"/>
...
</mets:seq>
</mets:fptr>
</mets:div>
</mets:div>
</mets:div>
</mets:structMap>
</mets:structSec>
</mets:mets>
Multiple <seq> elements would appear under a <par> element when multiple sequences of files or parts of files must be played/displayed simultaneously to manifest the content of the governing <fptr> element. See the section on the <par> element below for a more complete description of this case.
Presenting content simultaneously (in parallel): <par>
The <par> or parallel files element aggregates pointers to files, parts of files, and/or sequences of files or parts of files that must be played or displayed simultaneously to manifest a block of digital content represented by an <fptr> element.
This might be the case, for example, with multi-media content, where a still image might have an accompanying audio track that comments on the still image. In this case, a <par> element would aggregate two <area> elements, one of which pointed to the image file and one of which pointed to the audio file that must be played in conjunction with the image. The <area> element associated with the image could be further qualified with SHAPE and COORDS attributes if only a portion of the image file was pertinent and the <area> element associated with the audio file could be further qualified with BETYPE, BEGIN, EXTTYPE, and EXTENT attributes if only a portion of the associated audio file should be played in conjunction with the image.
Example 1
In the example below the <structMap> encoding uses the <par> element to recreate the experience and intent of the original analog source. In the source, a page of Latin text appears side by side with a page containing its English translation. The <par> elements here aggregate the images that represent the pairs of pages that must be displayed together to recreate this experience.
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams">
<mets:fileSec>
<mets:fileGrp USE="REFERENCE IMAGE">
<mets:file ID="epi09r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/09/jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi10r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/10.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi11r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/11.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi12r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/12.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi13r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/13.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi14r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/14.jpg"
LOCTYPE="URL"/>
</mets:file>
...
</mets:fileGrp>
</mets:fileSec>
<mets:structSec>
<mets:structMap TYPE="logical">
<mets:div TYPE="volume" LABEL="Martial Epigrams II">
<mets:div TYPE="section" LABEL="Book VIII">
<mets:div TYPE="paired pages" LABEL="page 1: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi09r"/>
<mets:area FILEID="epi10r"/>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="paired pages" LABEL="page 2: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi11r"/>
<mets:area FILEID="epi12r"/>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="paired pages" LABEL="page 3: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi13r"/>
<mets:area FILEID="epi14r"/>
</mets:par>
</mets:fptr>
</mets:div>
...
</mets:div>
</mets:div>
</mets:structMap>
</mets:structSec>
</mets:mets>
A <par> element can also aggregate <seq> elements representing sequences of files or parts of files that must be played or displayed simultaneously to manifest the content represented by an <fptr> This might be the case when a single bytestream which should be played in parallel with other streams is too large to fit in a single file (e.g., very high quality multi-track audio, or video). In these cases, you would use subsidiary <seq> elements, where each sequence identified the files comprising a particular bytestream in the order they should be played back.
The two potential subsidiary units — <area> and <seq> — may not both be used directly under the same <par> element; a <par> must contain either a set of <area> elements or a set of <seq> elements. In the case where a <par> element aggregates <seq> elements, however, the <seq> elements themselves will aggregate the <area> elements that point to the pertinent files or parts of files.
The example below demonstrates a use of <seq> elements within a <par> element. In this case, the <structMap> provides for the parallel display of Latin and English versions of the material where the Latin and English versions appear on separate pages in the analog source, and in separate sets of image files in the digital version. Furthermore, the <structMap> arranges the digital version of the material into a logical structure in which the divisions are manifested by just portions of the referenced integral image files. But, in the case of two divisions, that for the “Introduction” and that for “Book VIII, Epigram III,” the relevant portions of the material spans two image files. Therefore, the relevant areas of two image files must be displayed in sequence to manifest these divisions; and two different sequences must be displayed in parallel to manifest both Latin and English versions simultaneously.
Example 2
<mets:mets xmlns:mets="http://www.loc.gov/METS/v2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/METS/v2
http://www.loc.gov/standards/mets/mets.xsd"
OBJID="ark:/13030/kt9s2009hz" LABEL="Martial Epigrams">
<mets:fileSec>
<mets:fileGrp USE="REFERENCE IMAGE">
<mets:file ID="epi09r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/09.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi10r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards.mets/docgroup/jpg/10.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi11r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/11.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi12r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/12.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi13r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/13.jpg"
LOCTYPE="URL"/>
</mets:file>
<mets:file ID="epi14r" MIMETYPE="image/jpeg">
<mets:FLocat LOCREF="http://www.loc.gov/standards/mets/docgroup/jpg/14.jpg"
LOCTYPE="URL"/>
</mets:file>
</mets:fileGrp>
</mets:fileSec>
<mets:structSec>
<mets:structMap TYPE="logical">
<mets:div TYPE="volume" LABEL="Martial Epigrams II">
<mets:div TYPE="section" LABEL="Book VIII">
<mets:div TYPE="epigram" LABEL="Introduction: Latin & English">
<mets:fptr>
<mets:par>
<mets:seq>
<mets:area FILEID="epi09r" SHAPE="RECT" COORDS="0,1150,2500,3150"/>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,600,2500,900"/>
</mets:seq>
<mets:seq>
<mets:area FILEID="epi10r" SHAPE="RECT" COORDS="0,1100,2500,3300"/>
<mets:area FILEID="epi12r" SHAPE="RECT" COORDS="0,650,2500,950"/>
</mets:seq>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram I: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,1000,2500,1500"/>
<mets:area FILEID="epi12r" SHAPE="RECT" COORDS="0,950,2500,1600"/>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram II: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,1500,2500,2350"/>
<mets:area FILEID="epi12r" SHAPE="RECT" COORDS="0,1600,2500,2350"/>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram III: Latin & English">
<mets:fptr>
<mets:par>
<mets:seq>
<mets:area FILEID="epi11r" SHAPE="RECT" COORDS="0,2350,2500,3050"/>
<mets:area FILEID="epi13r" SHAPE="RECT" COORDS="0,500,2500,2100"/>
</mets:seq>
<mets:seq>
<mets:area FILEID="epi12r" SHAPE="RECT" COORDS="0,2350,2500,3050"/>
<mets:area FILEID="epi14r" SHAPE="RECT" COORDS="0,600,2500,2100"/>
</mets:seq>
</mets:par>
</mets:fptr>
</mets:div>
<mets:div TYPE="epigram" LABEL="Epigram IV: Latin & English">
<mets:fptr>
<mets:par>
<mets:area FILEID="epi13r" SHAPE="RECT" COORDS="0,2100,2500,2700"/>
<mets:area FILEID="epi14r" SHAPE="RECT" COORDS="0,2100,2500,2700"/>
</mets:par>
</mets:fptr>
</mets:div>
</mets:div>
</mets:div>
</mets:structMap>
</mets:structSec>
</mets:mets>