METS: Metadata Encoding and Transmission Standard.
METS is intended to provide a standardized XML format for transmission
of complex digital library objects between systems. As such, it can be seen
as filling a role similar to that defined for the Submission Information Package
(SIP), Archival Information Package (AIP), and Dissemination Information
Package (DIP) in the Reference Model for an Open Archival Information System.
dmdSec: Description Metadata Section.
This section records all of the descriptive metadata for all subobjects in the METS object.
Metadata can be either included in the METS hub document (mdWrap) or
referenced via an identifier/locator (mdRef), a la Warwick Framework. Multiple
mdRef and mdWrap elements are allowed so that descriptive metadata
can be recorded for each separate subobject within the METS object.
amdSec: Administrative Metadata Section.
This section records all of the administrative metadata for all subobjects in the METS object,
and is divided into three subsections: techMD (technical metadata), rightsMD
(intellectual property rights metadata), and sourceMD (provenance metadata).
Each of these subsections follows the mdSecType model, so that they can
either include metadata within the METS hub document (mdWrap) or
reference it via an identifier/locator (mdRef). Multiple
mdRef and mdWrap elements are allowed so that administrative metadata
can be recorded for each separate subobject within the METS object.
fileGrp: File Group.
File Groups record information regarding all of the data files comprising
the digital object, including both master files and derivatives. File Groups
may both repeat and nest to provide an organizing framework for data files.
structMap: Structural Map.
The structural map is the heart of a METS document, defining the
hierarchical arrangement of a primary source document which has
been digitized. This hierarchy is encoded as a tree of 'div' elements.
Any given 'div' can point to another METS document via the 'mptr'
element, or to a single file, to a group of files, or to segments of individual
files or groups of files through the 'fptr' and subsidiary elements.
div: Division of a structural map.
Nested div elements define the hierarchical structure of the digital library object.
Div elements are linked to the content corresponding to that div by subsidiary mptr and
fptr elements.
mets Complex Type.
A METS document consists of four possible subsidiary sections:
dmdSec (descriptive metadata section), amdSec (administrative
metadata section), fileGrp (file inventory group), and structMap
(structural map). It also has seven possible attributes:
1. ID (an XML ID);
2. OBJID: a primary identifier assigned to the original source
document;
3. LABEL: a title/text string identifying the document for
users;
4. TYPE: a type for the object, e.g., book, journal, stereograph, etc.;
5. CREATEDATE: the date the METS object was created;
6. LASTMODDATE: the date the METS object was last modifified; and
7. PROFILE: the registered profile to which this METS document conforms.
METS registry information is available from the Library of Congress at
http://www.loc.gov/mets.
amdSecType: Complex Type for Administrative Metadata.
The administrative metadata section consists of three possible subsidiary
sections: techMD (technical metadata for text/image/audio/video files),
rightsMD (intellectual property rights metadata), and sourceMD (source
metadata i.e. provenance). amdSecType
has a single attribute, ID (XML ID).
techMD: technical metadata.
The techMD element provides a wrapper around a generic metadata section,
which should contain technical metadata regarding a file or files. It has a single
attribute, ID, which file/fileGrp elements can use to reference the technical
metadata that applies to them.
rightsMD: intellectual property rights metadata.
The rightsMD element provides a wrapper around a generic metadata section,
which should contain IP rights metadata. It has a single attribute, ID, which
file/fileGrp/div elements can use to reference IP Rights metadata that applies to them.
sourceMD: source metadata.
The sourceMD element provides a wrapper around a generic metadata section
which should contain descriptive and administrative metadata regarding the
original, analog source material which was digitized to create the digital object.
In the case of born-digital objects, a separate section for source metadata may
not be necessary, although institutions using METS may want to record this
metadata to preserve a record of the original object should the content for
the digital object be transformed/migrated in the future. It has a single attribute,
ID, which file/fileGrp elements can use to reference the source metadata which
applies to them.
digiprovMD: digital provenance metadata.
The digiprovMD element provides a wrapper around a generic metadata
section, which should contain information regarding the ultimate origin of a digital
object and the derivation of its current elements. This includes recording
master/derivative relationships between various files which currently represent
the object, as well recording any transformations or migrations undergone
by files composing the digital object subsequent to the initial digitization of
an item or, in the case of born digital materials, the files' creation. In short,
digiprovMD should be used to record information to allow both archival/library
staff and scholars to understand what modifications have been performed to
a digital object during its life cycle in order to judge how those processes
might have altered or corrupted the object's ability to accurately represent
the original item.
fileGrpType: Complex Type for File Groups.
The file group is used to cluster all of the digital files composing a digital
library object in a hierarchical arrangement (fileGrp is recursively defined
to enable the creation of the hierarchy). Any file group may contain zero or
more file elements. File elements in turn can contain a FLocat element
(a pointer to a file containing content for this object) and/or a FContent
element (the contents of the file Base64 encoded). a fileGrp element
may have the following attributes:
1. ID: an XML ID for the element
2. VERSDATE: date this version/fileGrp of the digital object was created.
3. ADMID: IDREFs to administrative metadata sections in the METS document
that correspond with all files in this file group.
file: File element.
The file element provides access to content files for a METS document.
It has the following attributes:
1. ID: an XML ID for the element;
2. MIMETYPE: the MIME type for the file;
3. SEQ: an integer indicating the sequence of this file relative to the others in its file group;
4. SIZE: the size of the file in bytes;
5. CREATED: the date of creation for the file;
6. OWNERID: a primary identifier assigned to the file by its owner;
7. ADMID: IDREFS to administrative metadata sections in the METS document
that correspond with this file; and
8. GROUPID: an identifier that establishes a correspondence between this file
and files in other file groups. Typically, this will be used to associate a master
file in one file group with derivative files in other file groups.
A file element may contain an FLocat element, which provides a pointer to
a content file, and/or an FContent element, which wraps an encoded version
of the file.
FLocat: File Location.
The FLocat element provides a pointer to the location of a content file.
It has three attributes:
1. ID (an XML ID);
2. LOCTYPE: the type of locator contained in the FLocat element; and
3. OTHERLOCTYPE: a string to indicate an alternative LOCTYPE if
the LOCTYPE attribute itself has a value of "OTHER."
FContent: file content.
The FContent element is used to deliver a content file for a METS
document within the METS file itself. The content file must be Base 64
encoded, and contained within the FContent wrapper element. The
FContent element ahs the following attributes:
1. ID (an XML ID); and
2. CHECKSUM: an MD5 checksum value for the included file.
structMap Complex Type
The structural map (structMap) outlines a hierarchical structure for the
original object being encoded, using a series of nested div elements.
The structMap element has the following attributes:
1. ID: an XML ID for the element;
2. TYPE: the type of structural map provided. Typical values will be
"PHYSICAL" for a map which describes the physical composition of
the original work (a series with individual monographs with pages) and
"LOGICAL" for one which describes the intellectual structure of the work
(a monograph with TOC, forward, chapters, index., etc.);
3. LABEL: a string to describe the structMap to users. This is primarily
useful where more than one subject is provided for a single object
(e.g., both logical and physical structMap).
div: Division.
The METS standard represents a document structurally as a series of nested
div elements, that is, as a hierarchy (e.g., a book, which is composed of chapters,
which is composed of subchapters, which is composed of text). Every div node
in the structural map hierarchy may be connected (via subsidiary mptr or fptr
elements) to content files which represent that div's portion of the whole document.
Div Complex Type
The METS standard represents a document structurally as a series of nested
div elements, that is, as a hierarchy (e.g., a book, which is composed of chapters,
which is composed of subchapters, which is composed of text). Every div node
in the structural map hierarchy may be connected (via subsidiary mptr or fptr
elements) to content files which represent that div's portion of the whole document.
The div element has the following attributes:
1. ID (an XML ID);
2. ORDER: an integer representation of this div's order among its siblings
(e.g., its page number);
3. ORDERLABEL: a string representation of this div's order among its siblings (e.g., "Page xii");
4. LABEL: a string to describe this div to an end user viewing the document, as per
a table of contents entry;
5. TYPE: a string to describe the type of object/subobject represented by this div;
5. DMD: a set of IDREFs to descriptive metadata sections within this METS document
applicable to this div; and
6. ADMID: a set of IDREFS to administrative metadata sections within this METS document
applicable to this div.
mptr: METS Pointer.
The mptr element allows a div to be associated with a separate METS document
containing the content corresponding with that div, rather than pointing to an
internal file or file group. A typical instance of this would be the case of a METS
document for a journal run, with a div elements for each individual journal issue.
The div elements for the issues might point to separate METS documents for each
issue, rather than having files and file groups for every issue encoded in one
document. The mptr element may have the following attributes:
1. ID: an XML ID for this element;
2. LOCTYPE: the type of locator contained in the FLocat element; and
3. OTHERLOCTYPE: a string to indicate an alternative LOCTYPE if
the LOCTYPE attribute itself has a value of "OTHER."
fptr: File Pointer.
The fptr element associates a div element with content files that represent that div.
It can either point to a file directly itself, via the FILEID attribute, or it can do more
complex links to content via the subsidiary par and seq elements. The fptr
element can have the following attributes:
1. ID: an XML ID for this element; and
2. FILEID: an IDREF to a file element which corresponds with the div containing
this ftpr.
par: Parallel files.
The par element should used to link a div to a set of content files when
those files should be played back in unison to display the content to the
user. Individual area subelements within the par element provide the links
to the files or portions thereof. Par has the following attributes:
1. ID: an XML ID for this element.
seq: Sequence of files.
The seq element should be used to link a div to content files
when those files should be played sequentially to display content to a user.
Individual area subelements within the seq element provide the links
to the files or portions thereof. Seq has the following attributes:
1. ID: an XML ID for this element.
areaType: Complex Type for Area linking.
The area element provides for more sophisticated linking between a div
element and content files representing that div, be they text, image,
audio, or video files. An area element can link a div to a point
within a file, to a one-dimension segment of a file (e.g., text screen,
image line, audio/video clip), or a two-dimensional section of a file
(e.g, subsection of an image, or a subsection of the video display
of a video file. In addition to linking a div element directly with a file,
multiple area elements may be used within par or seq elements within
a div to link a div with areas in multiple files.The area element has no content,
and the following attributes:
1. ID: an XML ID;
2. FILEID: an IDREF to the file element being pointed to by the div;
3. SHAPE: a text string defining the shape of a two-dimensional
area being referenced in a link file;
4. COORDS: a text string representing a set of visual coordinates
within an image (still image or video frame). The COORDS and
SHAPE attributes should be used as in HTML 4;
5. BEGIN: a beginning location in a referenced file;
6. END: an ending location in a referenced file;
7. BETYPE: the syntax used in specifying the BEGIN and END
attributes (byte offset, IDREF value, one of the SMPTE time codes, SMIL
time value, MIDI time code, a simple time code of the form
HH:MM:SS, or a TCF time code);
8. EXTENT: the duraction of the segment; and
9. EXTTYPE: the syntax used in specifying the extent (byte length,
SMPTE time value, SMIL time value, MIDI time code, HH:MM:SS or
TCF time value).
mdSec (metadata section) Complex Type
A generic framework for pointing to/including metadata within a METS document,
a la Warwick Framework. An mdSec element may have the following attributes:
1. ID: an XML ID for this element.
mdRef: metadata reference.
The mdRef element is a generic element used throughout the METS schema
to provide a pointer to metadata which resides outside the METS document.
It has the following attributes:
1. ID: an XML ID;
2. LOCTYPE: the type of locator contained in the body of the element;
3. OTHERLOCTYPE: a string indicating an alternative LOCTYPE when the LOCTYPE
attribute value is set to "OTHER.";
4. MIMETYPE: the MIME type for the metadata being pointed at;
5. MDType: the type of metadata being pointed at (e.g., MARC, EAD, etc.);
6. OTHERMDTYPE: a string indicating an alternative MDTYPE when the MDTYPE
attribute value is set to "OTHER.";
7. LABEL: a label to display to the viewer of the METS document identifying the metadata; and
8. XPTR: an xptr to a location within the file pointed to by the mdRef element, if applicable.
mdWrap: metadata wrapper.
The mdWrap element is a generic element used throughout the METS schema to allow
the encoder to place arbitrary metadata conforming to other standards/schema within a
METS document. The included metadata can either be encoded in XML, in which case
it may be placed directly within the mdWrap element, or it can be Base64 encoded, and
placed within a subsidiary binData element. The mdWrap element can have the following
attributes:
1. ID: an XML ID for this element;
2. MIMETYPE: the MIME type for the metadata contained in the element;
3. MDType: the type of metadata contained (e.g., MARC, EAD, etc.);
4. OTHERMDTYPE: a string indicating an alternative MDTYPE when the MDTYPE
attribute value is set to "OTHER.";
5. LABEL: a label to display to the viewer of the METS document identifying the metadata.
A wrapper to contain Base64 encoded metadata.