METS.xml requirements

METS.xml is an XML document that conforms to the METS standard (Metadata Encoding and Transmission Standard). It is used to collect and structure metadata for a digital object within a single file. The file functions as a control and linking document that enables systems to understand, validate, and exchange complex digital objects in a standardized manner.

METS.xml describes:

The structure of the object (for example, how pages, chapters, or files are related).
File references to the digital files included (images, PDFs, audio files, etc.).
Metadata, which may be descriptive, administrative, and technical, often by referencing or embedding other metadata formats.

Information packages delivered to the DPS must include a METS.xml file in the root folder of the information package, as well as a METS.xml file in each representation folder.

Both METS.xml files must validate against the METS requirements specified by the E-ARK specifications CSIP1-119 and SIP1-35 in the E-ARK (C)SIP spesifikasjonene v2.2.0, in addition to the National Library’s specifications of SIP requirements described below (NBSIP).

Use of the METS root element (`mets`)

ID	Name, METS element, description	Requirement	Cardinality
NBSIP1	Package Identifier `mets/@OBJID` The `mets/@OBJID` attribute is mandatory, its value is a string identifier for the METS document. In the METS file located in the root folder of the package, this identifier MUST be identical to the name of the package’s root folder (see NBSIPSTR2 for formatting). In the METS files within the individual representation folders, this identifier MUST be identical to the name of the respective representation folder (see NBSIPSTR11 and NBSIPSTR12 for formatting). This requirement is a stricter version of CSIP1	MUST	1..1
NBSIP2	Package name `mets/@LABEL` A short text that provides the title or a description of the content of the information package. The value of the `mets/@LABEL` SHOULD match the “title” field in the API call. (see Metadata Requirements). This requirement is a stricter version of SIP1	SHOULD	1..1

Important

In addition to these requirements for the METS root element, there are a few media specific requirements that needs to be adhered to. These are found in the subpages below this page.

Example:

<mets xmlns="http://www.loc.gov/METS/"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:sip="https://DILCIS.eu/XML/METS/SIPExtensionMETS"
    xmlns:csip="https://DILCIS.eu/XML/METS/CSIPExtensionMETS"
    xmlns:xlink="http://www.w3.org/1999/xlink"    
    OBJID="no-nb_radio_NRKP2_199204081200"
    LABEL="no-nb_radio_NRKP2_199204081200"
    TYPE="Audio – On Tangible Medium (digital or analog)"
    csip:CONTENTINFORMATIONTYPE="OTHER"
    csip:OTHERCONTENTINFORMATIONTYPE="NB-METS-AUDIO-PROFILE-1.0"
    PROFILE="https://earksip.dilcis.eu/profile/E-ARK-SIP-v2-2-0.xml"
    xsi:schemaLocation="http://www.loc.gov/METS/ schemas/mets1_12.xsd http://www.w3.org/1999/xlink schemas/xlink.xsd https://dilcis.eu/XML/METS/CSIPExtensionMETS schemas/DILCISExtensionMETS.xsd https://dilcis.eu/XML/METS/SIPExtensionMETS schemas/DILCISExtensionSIPMETS.xsd">

Use of the METS header (`metsHdr`)

No further requirements beyond CSIP METS Header.

Use of the METS descriptive metadata section (`dmdSec`)

ID	Name, METS element, description	Requirement	Cardinality
NBSIP3	Descriptive metadata `mets/dmdSec` MUST be used to refer to available descriptive metadata about the information package. Each descriptive metadata section (`<dmdSec>`) contains a single description and must be repeated if multiple descriptions exist. See also NBSIPSTR9 which requires at least one file containing descriptive metadata. This requirement is a stricter version of CSIP17.	MUST	1..n
NBSIP4	Mandatory descriptive metadata `mets/dmdSec` The element describing the descriptive metadata section MUST refer to the metadata file(s) specified in NBSIPSTR9. It MUST be described using `mets/dmdSec/mdRef/@MDTYPE`. Valid values include: `MARC`, `MODS`, `EAD`, `DC`, `NISOIMG`, `LC-AV`, `VRA`, `TEIHDR`, `DDI`, `FGDC`, `LOM`, `PREMIS`, `PREMIS:OBJECT`, `PREMIS:AGENT`, `PREMIS:RIGHTS`, `PREMIS:EVENT`, `TEXTMD`, `METSRIGHTS`, `ISO 19115:2003 NAP`, `EAC-CPF`, `LIDO`, `OTHER`. If `OTHER` is selected, the type of metadata SHOULD be specified using `mets/dmdSec/mdRef/@MDOTHERTYPE`. Administrative or preservation metadata may be included in accordance with CSIP31-57.	MUST	1..n
NBSIP5	Reference to files with descriptive metadata `mets/dmdSec/mdRef` MUST be used to refer to files containing descriptive metadata located in the `metadata/descriptive`. Directly embedding of metadata using `mets/dmdSec/mdWrap` is discouraged. This requirement is a stricter version of CSIP21.	MUST	1..n
NBSIP6	File checksum type `mets/dmdSec/mdRef/@CHECKSUMTYPE` A value from the METS-standard which identifies the algorithm used to calculate the checksum for the referenced file. Checksum type MUST be : `MD5`. This requirement is a stricter version of CSIP29 og CSIP30.	MUST	1..1

Example:

<dmdSec ID="uuid-e1d1f6db-3851-40bf-9ffd-59277a4442dc" CREATED="2025-01-16T12:43:32.894+01:00" STATUS="CURRENT">
    <mdRef ID="ID-uuid-861d36a1-043f-45aa-b230-be13517823a9" LOCTYPE="URL" MIMETYPE="application/json" SIZE="2038" CREATED="2025-01-16T12:43:32.894+01:00" 
    CHECKSUM="EB72EF8AB5B1C93801DFACBFE6AA8E27" CHECKSUMTYPE="MD5" MDTYPE="DC" xlink:type="simple" xlink:href="metadata/descriptive/nb_dublincore.json"/>
</dmdSec>
<dmdSec ID="uuid-EC8718B5-C417-4D8C-975B-C14CD8197E62" CREATED="2025-01-16T12:43:32.894+01:00" STATUS="CURRENT">
    <mdRef ID="ID-uuid-FAF602A1-AB9A-44AC-A24B-B918F7064920" LOCTYPE="URL" MIMETYPE="text/xml" SIZE="1903" CREATED="2025-01-16T12:43:32.894+01:00" 
    CHECKSUM="50E9C929EAE5B51F20F8B86D604FD24D" CHECKSUMTYPE="MD5" MDTYPE="MODS" xlink:type="simple" xlink:href="metadata/descriptive/MODS.xml"/>
</dmdSec>

Use of the METS administrative metadata section (`amdSec`)

The E-ARK specification only defines how to reference digital provenance metadata (the digiprovMD section) and rights metadata (the rightsMD section) in METS. Digital provenance metadata refers to information about events in the lifecycle of the digital object. This data is typically formatted using PREMIS. Rights metadata contains information about intellectual property rights (IPR) associated with the digital objects.

However, the specification also allows for the inclusion of technical metadata (techMD section) and source metadata (sourceMD section). The National Library of Norway (NB) considers these metadata types essential for managing digital objects. Technical metadata describes the characteristics of the data itself, while source material metadata provides important context for the digital object and supports its authenticity. See also NBSIPSTR16 and NBSIPSTR17.

ID	Name, METS element, description	Requirement	Cardinality
NBSIP7	Source metadata `mets/amdSec/sourceMD` If metadata about the source material for a representation is available in the information package, this element MUST be used to describe it.	MUST	1..n
NBSIP8	Source metadata identifier `mets/amdSec/sourceMD/@ID` An `xml:id` identifier for the source metadata section `mets/amdSec/sourceMD` used for internal references within the XML document. The identifier MUST be unique within the XML document.	MUST	1..1
NBSIP9	Status of the source metadata `mets/amdSec/sourceMD/@STATUS` Status MUST be set to `CURRENT`	MUST	1..1
NBSIP10	Reference to files with the source metadata `mets/amdSec/sourceMD/mdRef` MUST be used to reference files containing source metadata located in the `metadata/source` folder. Direct embedding of metadata using `mets/amdSec/mdWrap` is discouraged.	MUST	1..1
NBSIP11	Type of locator `mets/amdSec/sourceMD/mdRef[@LOCTYPE='URL']` The locator type is always used with the value `URL` from Vocabulary status in the E-ARK specifications.	MUST	1..1
NBSIP12	Type of link `mets/amdSec/sourceMD/mdRef[@xlink:type='simple']` The attribute MUST be used with the value `simple`. The vocabulary of allowed values is maintained by the XLink standard.	MUST	1..1
NBSIP13	File location `mets/amdSec/sourceMD/mdRef/@xlink:href` The actual location of the file. It MUST be referenced using a URL of the filepath type.	MUST	1..1
NBSIP14	Type of metadata `mets/amdSec/sourceMD/mdRef/@MDTYPE` Specifies the type of metadata in the referenced file. The values are taken from METS. Valid values: `MARC`, `MODS`, `EAD`, `DC`, `NISOIMG`, `LC-AV`, `VRA`, `TEIHDR`, `DDI`, `FGDC`, `LOM`, `PREMIS`, `PREMIS:OBJECT`, `PREMIS:AGENT`, `PREMIS:RIGHTS`, `PREMIS:EVENT`, `TEXTMD`, `METSRIGHTS`, `ISO 19115:2003 NAP`, `EAC-CPF`, `LIDO`, `OTHER`. If `OTHER` is chosen, the type of metadata SHOULD be described using `mets/amdSec/sourceMD/mdRef/@MDOTHERTYPE`.	MUST	1..1
NBSIP15	Technical metadata `mets/amdSec/techMD` If technical metadata for the data files in a representation is available in the information package, this element MUST be used to describe it. Direct embedding of metadata using `mets/amdSec/mdWrap` is discouraged.	MUST	1..n
NBSIP16	Technical metadata identifier `mets/amdSec/techMD/@ID` An `xml:id` identifier for the technical metadata section `mets/amdSec/techMD` used for internal references within the XML document. The identifier MUST be unique within the XML document.	MUST	1..1
NBSIP17	Status of the technical metadata `mets/amdSec/techMD/@STATUS` Status MUST be set to `CURRENT`	MUST	1..1
NBSIP18	Reference to files with the technical metadata `mets/amdSec/techMD/mdRef` MUST be used to reference files containing technical metadata that are located in the folder `metadata/technical`.	MUST	1..1
NBSIP19	Type of locator `mets/amdSec/techMD/mdRef[@LOCTYPE='URL']` The locator type is always used with the value `URL` from Vocabulary status in the E-ARK specifications.	MUST	1..1
NBSIP20	Type of link `mets/amdSec/techMD/mdRef[@xlink:type='simple']` The attribute MUST be used with the value `simple`. The vocabulary of allowed values is maintained by the XLink standard.	MUST	1..1
NBSIP21	File location `mets/amdSec/techMD/mdRef/@xlink:href` The actual location of the file. It MUST be referenced using a URL of the filepath type.	MUST	1..1
NBSIP22	Type of metadata `mets/amdSec/techMD/mdRef/@MDTYPE` Specifies the type of metadata in the referenced file. The values are taken from METS. Valid values: `MARC`, `MODS`, `EAD`, `DC`, `NISOIMG`, `LC-AV`, `VRA`, `TEIHDR`, `DDI`, `FGDC`, `LOM`, `PREMIS`, `PREMIS:OBJECT`, `PREMIS:AGENT`, `PREMIS:RIGHTS`, `PREMIS:EVENT`, `TEXTMD`, `METSRIGHTS`, `ISO 19115:2003 NAP`, `EAC-CPF`, `LIDO`, `OTHER`. If `OTHER` is chosen, the type of metadata SHOULD be described using `mets/amdSec/techMD/mdRef/@MDOTHERTYPE`.	MUST	1..1
NBSIP23	File checksum type `mets/amdSec/digiprovMD/mdRef/@CHECKSUMTYPE, mets/amdSec/rightsMD/mdRef/@CHECKSUMTYPE, mets/amdSec/sourceMD/mdRef/@CHECKSUMTYPE, mets/amdSec/techMD/mdRef/@CHECKSUMTYPE` A value from the METS-standard which identifies the algorithm used to calculate the checksum for the referenced file. Checksum type MUST be : `MD5`. This requirement is a stricter version of CSIP43, CSIP44, CSIP56 og CSIP57.	MUST	1..1

Example:

<amdSec>
    <digiprovMD ID="uuid-975a7a15-140f-4e2c-a5ec-d136e86ea4e5" CREATED="2019-04-24T14:37:52.783+01:00">
        <mdRef LOCTYPE="URL" xlink:type="simple" xlink:href="metadata/preservation/events.xml"
            MDTYPE="PREMIS" MDTYPEVERSION="3.0" MIMETYPE="text/xml" SIZE="1211"
            CREATED="2018-04-24T14:37:52.783+01:00" CHECKSUM="dc7177d37a7de3448ee1e62da7343d72"
            CHECKSUMTYPE="MD5" LABEL="events.xml"/>
    </digiprovMD>
</amdSec>
<amdSec>
    <sourceMD ID="uuid-5d500e19-3802-49a5-92bd-7a575433ab7e" CREATED="2018-04-24T14:47:52.783+01:00">
        <mdRef LOCTYPE="URL" xlink:type="simple"
            xlink:href="metadata/souce/MAVIS_Carrier_12345_AE0000006261.xml" MDTYPE="OTHER"
            OTHERMDTYPE="MAVIS" MIMETYPE="text/xml" SIZE="2854"
            CREATED="2018-04-24T14:37:52.783+01:00" CHECKSUM="7ee30736137bfe72dc60afcbe374cb2a"
            CHECKSUMTYPE="MD5" LABEL="MAVIS_Carrier_12345_AE0000006261.xml"/>
    </sourceMD>
</amdSec>

Use of the METS file section (`fileSec`)

ID	Name, METS element, description	Requirement	Cardinality
NBSIP24	Sjekksumtype `mets/fileSec/fileGrp/file/@CHECKSUMTYPE` A value from the METS-standard which identifies the algorithm used to calculate the checksum for the referenced file. Checksum type MUST be : `MD5`. This requirement is a stricter version of CSIP71 og CSIP72.	MUST	1..1

Example:

<fileSec>
    <fileSec ID="file-sec-example">
        <mets:fileGrp ID="file-grp-doc" USE="Documentation">
        <mets:file ID="file-docx" 
        MIMETYPE="application/vnd.openxmlformats-officedocument.wordprocessingml.document" 
        SIZE="2554366" 
        CREATED="2012-08-15T12:08:15.432+01:00" 
        CHECKSUM="7ee30736137bfe72dc60afcbe374cb2a" CHECKSUMTYPE="MD5">
            <mets:FLocat LOCTYPE="URL" xlink:type="simple" xlink:href="documentation/File.docx">
</fileSec>

Use of the METS structural map (`structMap`)

No further requirements beyond CSIP METS structural map.

Last updated on 2026-01-20 - Github commit history ↗

METS.xml requirements

Use of the METS root element (mets)

Use of the METS header (metsHdr)

Use of the METS descriptive metadata section (dmdSec)

Use of the METS administrative metadata section (amdSec)

Use of the METS file section (fileSec)

Use of the METS structural map (structMap)

Use of the METS root element (`mets`)

Use of the METS header (`metsHdr`)

Use of the METS descriptive metadata section (`dmdSec`)

Use of the METS administrative metadata section (`amdSec`)

Use of the METS file section (`fileSec`)

Use of the METS structural map (`structMap`)