The representation level consists of at least one representation directory (in the remainder of this text we will use representation_1 as an example). Each representation directory contains information about the representation of (one of) the IE(s) of the package level, together with the media files making up the representation.
A representation directory consists of at least a METS.xml file, a /data directory and a /metadata directory. It contains both descriptive and preservation metadata, as well as the actual media files making up a certain representation of the IE(s) of the SIP.
Each representation directory contains its own METS.xml file which acts similarly as the package METS.xml and serves as an inventory of the files and directories of the representation level.
A representation directory may contain a /documentation and a /schemas directory. The former may contain additional information aiding the interpretation of the representation, while the latter may contain XML Schema Definition (XSD) files of the metadata schemas used in the representation. These two directories are ignored during ingest and will therefore not be archived.
Requirements
A representation directory MUST contain exactly one METS.xml file. The word METS in the filename MUST be written in all caps as displayed here.
The top level representation directory MUST have the value of the OBJID attribute in the METS.xml header as directory name. See mets/@OBJID for more details.
A representation directory MUST contain exactly one /metadata directory.
A representation directory MUST contain exactly one /data directory.
A representation directory MAY contain exactly one /documentation directory.
A representation directory MAY contain exactly one /schemas directory.
METS.xml (file)
The METS.xml file at the representation level (also known as the representation mets) generally follows the same structure and requirements as the package mets discussed in the section package METS.xml.
Elements and internal references
Since the dmdSec, amdSec, fileSec sections follow the same requirements (where possible) as the package METS.xml file, each dedicated subsection below only lists (additional) requirements regarding the mets, metsHdr and structMap elements.
Some of these elements, or their child elements, are identified with an identifier, contained in the @ID attribute (see the requirements in the sections below). These identifiers must be unique within the SIP.
The <structMap> serves as the entrypoint for locating the metadata, data or manifest files during parsing of the SIP. Therefore, it contains pointers to the @ID identifiers defined in the <fileSec>, <dmdSec>, and <amdSec> sections. An overview of the different elements and references on the representation level is given in the following figure.
Internal references between elements in the representation METS.xml.
In addition, the <fileGrp> and <file> elements can also reference contents of the <amdSec> and <dmdSec>, however this is optional. A summary of all possible references and their obligation is given in the table below.
This is an identifier for the representation METS document. Its value MUST be the same as the name of the top level representation folder (e.g., "representation_1" for the example above).
Textual works – Print Textual works – Digital Textual works – Electronic Serials Digital Musical Composition (score-based representations) Musical Scores - Print Musical Scores - Digital Photographs – Print Photographs – Digital Other Graphic Images – Print Other Graphic Images – Digital Microforms Audio – On Tangible Medium (digital or analog) Audio – Media-independent (digital) Motion Pictures – Digital and Physical Media Video – File-based and Physical Media Software Software and Video Games Email Datasets Geospatial Data Geographic Information System (GIS) - Vector Data GIS Raster and Georeferenced Images GIS Vector and Raster Combined Non-GIS Cartographic 2D and 3D Computer Aided Design Design (schematics, architectural drawings) - Print Scanned 3D Objects (output from photogrammetry scanning) Databases Websites Web Archives Collection Event Image Interactive resource Moving image Sound Still image Text Physical object Service Mixed Other
Cardinality
1..1
Obligation
MUST
Attribute
mets[@TYPE="OTHER"]/@csip:OTHERTYPE
Name
Other content category
Description
When the mets/@TYPE attribute is set to OTHER, the mets/@csip:OTHERTYPE attribute SHOULD be used to declare the content category of the representation not contained in the fixed vocabulary of the @TYPE attribute.
In case the representation was modified since its creation, this attribute records the date and time of that modification. This attribute MUST be present and used when the representation has been modified since its creation datetime.
A way of indicating the status of the representation and to instruct meemoo on how to properly handle it. If not set, the expected value is NEW. Meemoo investigates the use of the @RECORDSTATUS attribute for future use cases such as e.g. a metadata update (i.e. ingest of metadata only with the goal of updating, adding or deleting existing metadata in meemoo’s archive system).
The structMap element outlines the hierarchical structure of the representation level of the SIP. Its requirements are very similar to the package level, however, instead of pointing to the contained representations, a data division points to the contained files.
All file groups containing content described in the package are referenced via the relevant file group identifiers. There MUST be one file group reference per fptr element.
The pointer to the identifier for the data file group. This identifier MUST correspond to an identifier of a file/@ID attribute in the fileSec section of the METS file.
The /data directory contains the media files of a specific representation of the SIP. Depending on the use-case and the CP, these files can be digital pictures, video, audio…
Requirements
The /data directory MUST NOT contain any subdirectories.
All files in the /data directory MUST be referenced in the corresponding representation METS.xml file.
/metadata (directory)
The /metadata directory contains both descriptive and preservation metadata about the representation and the media files at the representation level.
Requirements
The /metadata directory MUST contain the subdirectory /preservation and it MAY contain the /descriptive subdirectory.
/descriptive (directory)
The /descriptive directory contains descriptive metadata about the representation. This descriptive metadata is stored in XML files, describing the specific representation of the SIP.
Descriptive metadata at the represenation level follows the same requirements regarding metadata elements discussed in the /descriptive section of the package level. Hence, the concrete requirements of descriptive metadata files and the applied metadata schemas are defined by the content profiles.
/preservation (directory)
The /preservation directory contains preservation metadata about the representation and the media files.
Requirements
The /preservation directory MUST contain exactly one file: premis.xml.
The premis.xml file of the representation level contains preservation metadata about the representation and the media files of the representation level. It relies on the PREMIS standard in order to provide basic preservation information such as checksums. More detailed preservation information can be described using PREMIS events and PREMIS agents.
Example
<?xml version="1.0" encoding="UTF-8"?><premis:premisversion="3.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:premis="http://www.loc.gov/premis/v3"xsi:schemaLocation="http://www.loc.gov/premis/v3 https://www.loc.gov/standards/premis/premis.xsd"><premis:objectxsi:type="premis:representation"><premis:objectIdentifier><premis:objectIdentifierType>UUID</premis:objectIdentifierType><premis:objectIdentifierValue>uuid-541292c3-223a-4b80-b747-66bc86ff4a89</premis:objectIdentifierValue></premis:objectIdentifier><!-- relationship between representation and its files --><premis:relationship><premis:relationshipTypeauthority="relationshipType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipType/str">structural</premis:relationshipType><premis:relationshipSubTypeauthority="relationshipSubType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType/inc">includes</premis:relationshipSubType><premis:relatedObjectIdentifier><premis:relatedObjectIdentifierType>UUID</premis:relatedObjectIdentifierType><premis:relatedObjectIdentifierValue>uuid-bd610fa4-077c-40cc-a278-74220df0a0c1</premis:relatedObjectIdentifierValue></premis:relatedObjectIdentifier><premis:relatedObjectIdentifier><premis:relatedObjectIdentifierType>UUID</premis:relatedObjectIdentifierType><premis:relatedObjectIdentifierValue>uuid-950ea040-5e79-4223-b804-b76660ec7e85</premis:relatedObjectIdentifierValue></premis:relatedObjectIdentifier></premis:relationship><!-- relationship between representation and its IE --><premis:relationship><premis:relationshipTypeauthority="relationshipType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipType/str">structural</premis:relationshipType><premis:relationshipSubTypeauthority="relationshipSubType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType/rep">represents</premis:relationshipSubType><premis:relatedObjectIdentifier><premis:relatedObjectIdentifierType>UUID</premis:relatedObjectIdentifierType><premis:relatedObjectIdentifierValue>uuid-948e2213-ca54-459c-8c87-5818adeb9444</premis:relatedObjectIdentifierValue></premis:relatedObjectIdentifier></premis:relationship></premis:object><premis:objectxsi:type="premis:file"><premis:objectIdentifier><premis:objectIdentifierType>UUID</premis:objectIdentifierType><premis:objectIdentifierValue>uuid-bd610fa4-077c-40cc-a278-74220df0a0c1</premis:objectIdentifierValue></premis:objectIdentifier><premis:objectCharacteristics><premis:fixity><premis:messageDigestAlgorithmauthority="cryptographicHashFunctions"authorityURI="http://id.loc.gov/vocabulary/preservation/cryptographicHashFunctions"valueURI="http://id.loc.gov/vocabulary/preservation/cryptographicHashFunctions/md5">
MD5
</premis:messageDigestAlgorithm><premis:messageDigest>b7ae37f6094794e313402b9d064978e8</premis:messageDigest></premis:fixity><premis:size>721603</premis:size><premis:format><premis:formatRegistry><premis:formatRegistryName>PRONOM</premis:formatRegistryName><premis:formatRegistryKey>fmt/1507</premis:formatRegistryKey><premis:formatRegistryRoleauthority="formatRegistryRole"authorityURI="http://id.loc.gov/vocabulary/preservation/formatRegistryRole"valueURI="http://id.loc.gov/vocabulary/preservation/formatRegistryRole/spe">specification</premis:formatRegistryRole></premis:formatRegistry></premis:format></premis:objectCharacteristics><premis:originalName>1445.jpeg</premis:originalName><!-- relationship between file and its representation --><premis:relationship><premis:relationshipTypeauthority="relationshipType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipType/str">structural</premis:relationshipType><premis:relationshipSubTypeauthority="relationshipSubType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType/isi">is included in</premis:relationshipSubType><premis:relatedObjectIdentifier><premis:relatedObjectIdentifierType>UUID</premis:relatedObjectIdentifierType><premis:relatedObjectIdentifierValue>uuid-541292c3-223a-4b80-b747-66bc86ff4a89</premis:relatedObjectIdentifierValue></premis:relatedObjectIdentifier></premis:relationship></premis:object><premis:objectxsi:type="premis:file"><premis:objectIdentifier><premis:objectIdentifierType>UUID</premis:objectIdentifierType><premis:objectIdentifierValue>uuid-950ea040-5e79-4223-b804-b76660ec7e85</premis:objectIdentifierValue></premis:objectIdentifier><premis:objectCharacteristics><premis:fixity><premis:messageDigestAlgorithmauthority="cryptographicHashFunctions"authorityURI="http://id.loc.gov/vocabulary/preservation/cryptographicHashFunctions"valueURI="http://id.loc.gov/vocabulary/preservation/cryptographicHashFunctions/md5">
MD5
</premis:messageDigestAlgorithm><premis:messageDigest>d4985ba4b67ff067a0e84c53b6d35355</premis:messageDigest></premis:fixity><premis:size>738611</premis:size><premis:format><premis:formatRegistry><premis:formatRegistryName>PRONOM</premis:formatRegistryName><premis:formatRegistryKey>fmt/1507</premis:formatRegistryKey><premis:formatRegistryRoleauthority="formatRegistryRole"authorityURI="http://id.loc.gov/vocabulary/preservation/formatRegistryRole"valueURI="http://id.loc.gov/vocabulary/preservation/formatRegistryRole/spe">specification</premis:formatRegistryRole></premis:formatRegistry></premis:format></premis:objectCharacteristics><premis:originalName>1450.jpeg</premis:originalName><!-- relationship between file and its representation --><premis:relationship><premis:relationshipTypeauthority="relationshipType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipType/str">structural</premis:relationshipType><premis:relationshipSubTypeauthority="relationshipSubType"authorityURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType"valueURI="http://id.loc.gov/vocabulary/preservation/relationshipSubType/isi">is included in</premis:relationshipSubType><premis:relatedObjectIdentifier><premis:relatedObjectIdentifierType>UUID</premis:relatedObjectIdentifierType><premis:relatedObjectIdentifierValue>uuid-541292c3-223a-4b80-b747-66bc86ff4a89</premis:relatedObjectIdentifierValue></premis:relatedObjectIdentifier></premis:relationship></premis:object></premis:premis>
Overview of relevant PREMIS relationships
On the representation level, the preservation metadata is used to express
what the representations and files are that are contained in the SIP; and
how they relate to eachother or to IEs described on the package level.
The table below gives an overview of the different relationship types that can be used on the representation level:
This attribute signals which PREMIS version is being used. The attribute’s value MUST be set to 3.0.
Cardinality
1..1
Obligation
MUST
Attribute
premis:premis/@xsi:schemaLocation
Name
Schema location declaration
Description
This attribute signals where to find the relevant XSD schema in order to validate the PREMIS file.
When used, its value MUST be set to "http://www.loc.gov/premis/v3 https://www.loc.gov/standards/premis/premis.xsd" to signal conformance with PREMIS 3.0.
Cardinality
0..1
Obligation
SHOULD
Element
premis:premis/premis:object
Name
PREMIS object
Description
A premis:object element MUST be defined for each representation and file of the representation level in the SIP.
Cardinality
1..*
Obligation
MUST
Attribute
premis:premis/premis:object/@xsi:type
Name
Object type
Description
This attribute signals whether a PREMIS object is of type intellectual entity, representation or file.
In the case of the premis.xml file of the representation level, this attribute’s value MUST be set to premis:representation in the case of a representation object, and to premis:file in the case of a file object.
This element contains object identifier information.
There MUST be exactly one object identifier present with premis:objectIdentifierType set to UUID. This is the main identifier for the concerned representation or file, which uniquely identifies the concerned IE and establishes a link between the relevant preservation metadata in the premis.xml file and the descriptive metadata in the dc*.xml file, if any is present. There MAY be zero or more additional object identifiers of a different type.
The type of the PREMIS object identifier being used.
At least one identifier of type UUID MUST be defined in order to provide a unique identifier for each PREMIS object.
This unique identifier is also used to link the concerned PREMIS object with the descriptive metadata in the /metadata/descriptive/dc*.xml file, if any is present.
The actual value that makes up the identifier of the PREMIS object.
Datatype
String (depending on the value of the premis:objectIdentifierType)
Cardinality
1..1
Obligation
MUST
Element
premis:premis/premis:object/premis:relationship
Name
PREMIS relationship
Description
Information about a relationship between the current object and one or more other objects.
In the case of the premis.xml file of the representation level, this element MUST detail the relationships between the representation and IE on the one hand, and between the representation and file(s) on the other hand.
This attribute indicates the name of the authority/controlled vocabulary that is being used for the different relationship types. Its value MUST be set to "relationshipType".
This attribute references the URI that contains the authority/controlled vocabulary. Its value MUST be set to "http://id.loc.gov/vocabulary/preservation/relationshipType".
A detailed categorization of the nature of the relationship.
In the case of the premis.xml file of the representation level, this element’s value MUST be set to represents when expressing the relationship between a representation and the IE it represents. When expressing the relationship between a representation and a file, this element’s value MUST be set to includes when this relationship is expressed from the side of the representation (i.e. the representation is the subject of the relationship); when this relationship is expressed from the side of the file (i.e. the file is the subject of the relationship), this element’s value MUST be set to is included in.
This attribute indicates the name of the authority/controlled vocabulary that is being used for the different relationship subtypes. Its value MUST be set to "relationshipSubType".
This attribute references the URI that contains the authority/controlled vocabulary. Its value MUST be set to "http://id.loc.gov/vocabulary/preservation/relationshipSubType".
This attribute references the URI that contains the specific entry from the authority/controlled vocabulary.
If the represents relationship subtype is being used, this attribute’s value MUST be set to "http://id.loc.gov/vocabulary/preservation/relationshipSubType/rep". If the includes relationship subtype is being used, this attribute’s value MUST be set to "http://id.loc.gov/vocabulary/preservation/relationshipSubType/inc". If the is included in relationship subtype is being used, this attribute’s value MUST be set to "http://id.loc.gov/vocabulary/preservation/relationshipSubType/isi"
If the PREMIS object is of type file, this element MUST be used to further specify the various characteristics of the file object such as fixity, size and format information.
This attribute indicates the name of the authority/controlled vocabulary that is being used for the different message digest algorithms. Its value MUST be set to "cryptographicHashFunctions".
This attribute references the URI that contains the authority/controlled vocabulary. Its value MUST be set to "http://id.loc.gov/vocabulary/preservation/cryptographicHashFunctions".
This element contains information about the format of the file object. At least one of premis:formatDesignation or premis:formatRegistry MUST be present.
This attribute indicates the name of the authority/controlled vocabulary that is being used. Its value MUST be set to "http://id.loc.gov/vocabulary/preservation/formatRegistryRole".
