NOTE: This page is currently under development and should be considered a draft. If you wish to contribute, please contact the authors.

Notes from a recent meeting concerning the CMDI specification can be found here

Component Metadata Infrastructure (CMDI) 1.2 [DRAFT]

Introduction

The goal of the Component Metadata Infrastructure (CMDI) specification...

TODO

History

TODO

Terminology

The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted as described in RFC2119.

Glossary

Work in progress. Responsible for this section: Thorsten & Twan

Please do not edit here, but use the ​Google Docs version!

• CMD model, Component Metadata model
  • The component based metadata model described in the present specification
• CMDI, Component Metadata Infrastructure
  • Metadata description framework consisting of the CMD model and infrastructure
• CCSL, CMDI Component Specification Language
  • XML based language for describing components according to the CMD model
• CLARIN
  • The infrastructure governed by the CLARIN ERIC
  • ​http://www.clarin.eu

• resource, language resource
  • A (digitally) accessible entity that can be described in terms of its content and technical properties, referenced by a Uniform Resource Identifier
• digital object
  • Resource in a repository stored in one repository container that can be addressed by an identifier; a digital object can be seen as a generalization of a directory in a file system containing one or more files which are the data stream(s). Digital objects can exist in databases, hence the comparison to directory and file structures falls short.

• metadata
  • A description of a resource, usually given as a set of properties in the form of attribute-value pairs. This description may contain information about the resource, aspects or parts of the resource and/or artefacts and actors connected to the resource.
• persistent identifier, PID
  • Unique Uniform Resource Identifier that assures permanent access for a digital object by providing access to it independently of its physical location or current ownership

• concept
  • An abstract or generic idea generalized from particular instances (source: ​Merriam-Webster)
• semantic registry
  • A list/directory/system maintaining (authoritative) definitions of terms, concepts or data categories. These registries should also provide persistent identifiers for their entries.
• concept link
  • A reference from a CMD profile, CMD component, CMD element, CMD attribute or a value in a controlled vocabulary to an entry in a semantic registry via its persistent identifier.
• CLARIN Concept Registry
  • The semantic registry maintaining concepts used/central to the CLARIN infrastructure
  • ​http://clarin.eu/ccr

• XML
  • Markup language standard as described by W3C recommendation ​http://www.w3.org/TR/xml/
• XML document
  • ...
• XML element
  • A constituent of an XML document as defined in W3C recommendation ​http://www.w3.org/TR/xml/ (distinct from a CMD element)
• XML schema datatype
  • A predefined set of permissible content within a section of an XML document as described in ​http://www.w3.org/TR/xmlschema-2/
• XML container element
  • An XML element that has one or more XML elements as its descendants
• XML attribute
  • A property of an XML element as defined in W3C recommendation ​http://www.w3.org/TR/xml/ (distinct from a CMD attribute)
• Uniform Resource Identifier, URI
  • An identifier for resources as described in ​RFC3986
• namespace
  • An XML namespace as described in ​http://www.w3.org/TR/xml-names/

• CMD instance, metadata instance, CMDI file, metadata record, CMD record
  • A file that conforms to the general CMDI instance structure as described in this specification, and at the instance payload level follows the specific structure defined by the CMD specification it relates to
• Instance header
  • The section of a metadata instance marked as ‘header’, providing information on that metadata instance as such, not the resource that is described by the metadata file
• Resource proxy, CMD resource reference
  • A representation of a resource within a metadata instance containing a Uniform Resource Identifier as a reference to the resource itself and a specification of its type (one of: Resource, Metadata, SearchPage, SearchService, LandingPage)
• Resource proxy reference
  • A reference from any point within the CMD instance payload to any of the resource proxies
• CMD instance payload(?)
  • The section of a metadata instance that follows the structure defined by the profile it references and contains the description of the resources to which that metadata instance relates
• CMD instance envelope (?)
  • [todo]

• CMD specification, component specification/definition, profile specification/definition
  • The implementation of a CMD component or CMD profile by means of the CCSL
• Specification header, component header, profile header
  • The section of a CMD specification marked as ‘header’, providing information on that specification as such that is not part of the defined structure
• CMD component, component
  • A reusable, structured template for the description of (an aspect of)a resource, defined by means of a CMD specification document with the potential of embedding other components by reference
• CMD profile, profile definition, profile
  • A CMD component that is used to describe a class of resources and is not embedded into other components, and therefore provides the complete structure for an instance payload
• CMD element, element definition
  • A unit of a CMD component that describes the level of the metadata instance that can carry atomic values constrained by a value scheme, and does not contain further levels except for that of the CMD attribute
• CMD attribute
  • A unit of a CMD element that describes the level at which properties of a CMD element can be provided by means of value scheme constrained atomic values.

• value scheme
  • A set of constraints governing the range of  values allowed for a specific CMD element or CMD attribute in a metadata instance, expressed in terms of an XML schema datatype, controlled vocabulary, or regular expression
• controlled vocabulary, closed/open vocabulary
  • A set of values that can be used either to constrain the set of permissible values or to provide suggestions for applicable values in a given context
• regular expression
  • An expression that constrains the set of permissible values,as described in  XML Schema Regular Expressions ​http://www.w3.org/TR/xmlschema-2/#regexs
• CMD profile schema
  • A schema definition by which the correctness of a CMD instance with respect to the CMD profile it pertains to can be evaluated. May be expressed as XML Schema but also in another XML schema language.
• XML element declaration
  • todo e.g. xs:element
• XML attribute declaration
  • todo e.g. xs:attribute

Normative References

RFC2119

Key words for use in RFCs to Indicate Requirement Levels, IETF RFC 2119, March 1997,
​http://www.ietf.org/rfc/rfc2119.txt

XML-Namespaces

Namespaces in XML 1.0 (Third Edition), W3C, 8 December 2009,
​http://www.w3.org/TR/2009/REC-xml-names-20091208/

Non-Normative References

RFC3023

XML Media Types, IETF RFC 3023, January 2001,
​http://www.ietf.org/rfc/rfc3023.txt

Typographic and XML Namespace conventions

The following typographic conventions for XML fragments will be used throughout this specification:

• <prefix:Element>
  An XML element with the Generic Identifier Element that is bound to an XML namespace denoted by the prefix prefix.
• @attr
  An XML attribute with the name attr
• string
  The literal string must be used either as element content or attribute value.

The following XML namespace names and prefixes are used throughout this specification. The column "Recommended Syntax" indicates which syntax variant SHOULD be used by the toolkit and other creators of CMDI related documents.

Prefix	Namespace Name	Comment	Recommended Syntax
cmd	http://www.clarin.eu/cmd/1	CMDI instance (general/envelope)	prefixed
cmdp	http://www.clarin.eu/cmd/1/profiles/{profileId}	CMDI payload (profile specific)	prefixed
cue	http://www.clarin.eu/cmd/cues/1	Cues for tools	prefixed
xs	http://www.w3.org/2001/XMLSchema	XML Schema	prefixed

Structure of CMDI files

Responsible for this section: Oddrun

A CMDI file contains the actual metadata of one specific resource (hereafter referred to as the described resource), and might also be referred to as a CMD record. All CMDI files have the same structure at the top level. At a lower level, parts of its structure are defined by the CMD profile upon which it is based.

The main structure

A CMDI file has the root element <CMD> with 4 subelements:

• The <Header> element, containing certain administrative information about the CMDI file, i.e. metadata about the file itself
• The <Resources> element, listing resource proxies and their interrelations, by the following subelements (ordered)
  • <ResourceProxyList>, containing a list of <ResourceProxy> elements, each referencing a file contained in or closely related to the described resource
  • <JournalFileProxyList>, containing a list of <JournalFileProxy> elements, each referencing a file (“journal file”) containing provenance information about the described resource
  • <ResourceRelationList>, containing a list of <ResourceRelation> elements, each representing a relationship between 2 resource files (as listed in the <ResourceProxyList>)
• The <IsPartOfList> element, containing a list of <IsPartOf> elements, each referencing a larger external resource of which the described resource (as a whole) forms a part
• The <Components> element, containing one subelement corresponding to – and in turn structured according to - the CMD profile applied. Here the "real" metadata of the reosurce are to be found.

The first three elements (<Header>, <Resources>and <IsPartOfList>) constitute the CMD instance envelopeand reside in the cmd namespace. The CMD instance payload contains the <Components>element, which (profile specific) substructure exists in the profile-specific namespace (prefix cmdp) or cues-for-tools namespace (cue).

A detailed specification of the above mentioned parts of a CMD instance is given in the next four sections. In addition to this, foreign attributes (XML attributes of other namespaces than those defined in the [Typographic and XML Namespace conventions]) MAY occur anywhere in <Header>, <Resources>and <IsPartOfList>elements and on the <Components> element (but not on any of its children).

The <Header> element

The header of a CMDI file mainly contains administrative information about the metadata, that is metadata about the CMDI file itself. The following elements may be included in the order indicated:

Name		Value type	Occurrences	Description
<Header>		xs:complexType	1	Encapsulates core admistrative data about the CMDI file
	<MdCreator>	xs:string	0 to unbounded	Denotes the creator of this metadata file
	<MdCreationDate>	xs:date	0 or 1	The date this metadata file was created
	<MdSelfLink>	xs:anyURI	0 or 1	A reference to this metadata file in its home repository, in the form of a PID (preferred) or a URL
	<MdProfile>	xs:anyURI	1	The CMDI profile upon which this metadata file is based, given by its identifier in the Component Registry, e.g. clarin.eu:cr1:p_1407745711925
	<MdCollectionDisplayName>	xs:string	0 or 1	The collection to which the described resource belongs, given as a human-readable name. In VLO this name will be assigned to the Collection facet.

The <Resources> element

This section of the CMDI file enumerates

• files which are parts of or closely related to the described resource (<ResourceProxyList> and <JournalFileProxyList>)
• possible relations between pairs of these files (<ResourceRelationList>)
• any external resources of which the described resource is a part (<IsPartOfList>)

The list of resource proxies

<ResourceProxyList> contains a sequence of zero or more occurrences of <ResourceProxy>, each of which representing a file/part of the described resource.

Name				Value type	Occurrences	Description
<ResourceProxyList>				xs:complexType	1	Contains a list of resource proxies (see below)
	<ResourceProxy>			xs:complexType	0 to unbounded	Represents a file which is a part of or closely related to the described resource
		@id		xs:ID	1	Local identifier for the parent <ResourceProxy>, unique within this CMDI file
		<ResourceType>		Value from controlled set (cmd:Resourcetype_simple): Resource,Metadata,LandingPage,SearchService,SearchPage	1	The type of the file represented by this <ResourceProxy>
			@mimeType	xs:string	0 or 1	The media type of the file
		<ResourceRef>		xs:anyURI	1	A reference to the file represented by this <ResourceProxy>, in the form of a Clarin compliant PID or a regular URL

The list of journal files

<JournalFileProxyList> contains a sequence of zero or more occurrences of <JournalFileProxy>, each of which representing a file containing provenance information about the described resource.

Name			Value type	Occurrences	Description
<JournalFileProxyList>			xs:complexType	1	Contains a list of journal file proxies (see below)
	<JournalFileProxy>		xs:complexType	0 to unbounded	Represents a file containing provenance information about the described resource
		<JournalFileRef>	xs:anyURI	1	A reference to the file represented by this <JournalFileProxy>, in the form of a Clarin compliant PID or a regular URL

The list of relations between resource files

<ResourceRelationList> contains a sequence of zero or more occurrences of <ResourceRelation>, each of which representing a relation between any pair of <ResourceProxies>.

Name					Value type	Occurrences	Description
<ResourceRelationList>					xs:complexType	1	A representation of a relation between 2 resource proxies listed in <ResourceProxyList>
	<ResourceRelation>				xs:complexType	0 to unbounded	A representation of a relation between 2 resource proxies listed in <ResourceProxyList>
		<RelationType>			xs:string	1	The type of the relation represented by its parent <ResourceRelation>
			@ConceptLink		xs:anyURI	0 or 1	A reference to some concept registry (Clarin Concept Registry by default), indicating the semantics of <RelationType>
		<Resource>			xs:complexType	2	References one of the resource proxies participating in the relationship
			@ref		xs:IDREF	1	A reference to the <ResourceProxy> with id=ref (the <ResourceProxy> represented by its parent <Resource> element)
			<Role>		xs:string	0 or 1	Indicates the role its parent Resource plays in the relationship
				@ConceptLink	xs:anyURI	0 or 1	A reference to some concept registry (Clarin Concept Registry by default), indicating the semantics of <RelationType>

The IsPartOf List

<IsPartOfList> contains a sequence of zero or more occurrences of <IsPartOf>, each representing an external resource of which the described resource constitutes a part.

Name		Value type	Occurrences	Description
<IsPartOfList>		xs:complexType	0 or 1	Contains a list of <IsPartOf>(see below)
	<IsPartOf>	xs:anyURI	0 to unbounded	A reference to an external resource of which the described resource is a part, in the form of a Clarin compliant PID or a regular URL

The components

Sate purpose of components section, and its dependency upon profile (as given in header: MdProfile?)

The CMDI Component Specification Language (CCSL)

Responsible for this section: Thomas

The CMDI Component Specification Language (CCSL) is used to describe a CMD component or CMD profile. Hence, a CCSL document provides the structure for describing an aspect of a resource or (in the case of a profile specification) the complete structure of the CMD instance. It is also basis for the generation of the XML schema file that is used to validate a CMD instance (see section Transformation of CCSL into a CMD schema definition for details).

A CCSL document MUST contain a CCSL header and the actual CMD component description. Its root element MUST contain an XML attribute isProfile to indicate if the document specifies a CMD profile or a CMD component.

Name		Valuetype	Occurrences	Description
<ComponentSpec>		xs:complexType	1	Root element of the CCSL document
	<Header>	xs:complexType	1	Header of the component specification
	<Component>	xs:complexType	1	Definition of the component's structure
	@isProfile	xs:boolean	1	Indication about the component's status as a profile

CCSL header

The CCSL header provides information relevant to identify and describe the component. This part includes a persistent identifier, the name, the description of the component and information about the status of the specification. The header MUST contain an element indicating the component's status in its lifecycle (using the three lifecycles development, production, or deprecated) and MAY contain the element statusComment to contain information about the reason for the current status. In the case of a deprecated specification that was succeeded by a new specification, the identifier of the direct successor MAY be stored in the element Successor.

Name		Valuetype	Occurrences	Description
<Header>		xs:complexType		Descriptive information about the component
	<ID>	xs:anyURI	0 or 1	ID of the component specification
	<Name>	xs:string	0 or 1	Name of the component
	<Description>	xs:string	0 or 1	Description of the component
	<Status>	xs:string ("development", "production", "deprecated")	1	Status in lifecycle
	<StatusComment>	xs:string	0 or 1	Comment about the status
	<Successor>	xs:anyURI	0 or 1	ID of successor component, if available

CMD component definition

Components are defined as a sequence of elements which MAY be followed by other components. The latter is allowed because components may be embedded in other components. If an already defined CMD component (i.e. a CMD component with its own identifier) should be referenced, @ComponentId MUST be used to indicate its identifier. If this is not the case, the specification of a CMD components MAY contain the name of the component, the component's identifier, a concept link, and information about the allowed cardinality of the component. Furthermore documentation texts and further CMD attributes MAY be specified.

Name		Valuetype	Occurrences	Description
<Component		xs:complexType		Root element of every CMD component definition
	@name	xs:Name	0 or 1	Name of the component
	@ComponentId	xs:anyURI	0 or 1	Identifier of the component
	@ConceptLink	xs:anyURI	0 or 1	Concept link
	@CardinalityMin	xs:nonNegativeInteger	0 or 1	Minimum number of times this component has to occur
	@CardinalityMax	xs:nonNegativeInteger or “unbounded”	0 or 1	Maximum number of times this component may occur
	Documentation	xs:string	0 to unbounded	Documentation about the purpose of the component
	AttributeList	xs:complexType	0 or 1	Additional attributes specified by the component creator

CMD element definition

CMD elements are a template for storing atomic values constrained by a value scheme in a CMD instance. The CCSL specification of an CMD element MUST contain the name of the element and MAY contain a concept link, the value schema, and information about the allowed cardinality of the element. Furthermore it MAY be indicated if the element may have different instance values in multiple languages, and hence an unlimited upper cardinality bound. Besides standard XML schema datatypes the value of a CMD element MAY be constrained by using regular expressions or vocabularies. The latter can be specified by giving the complete list of allowed values or by stating the URI of an external vocabulary (for details see Value restrictions for elements and attributes). If the instance's content of the element can be derived from other values, the element AutoValue MAY be used to give indication about the derivation function. The CCSL does not prescribe or suggest a specific set of derivation functions.

Name		Valuetype	Occurrences	Description
<Element>		xs:complexType		Root element of every CMD element definition
	@name	xs:Name	1	Name of the element
	@ConceptLink	xs:anyURI	0 or 1	Concept link
	@ValueScheme	Subset of XSD datatypes	0 or 1	Allowed data type if simple XML type is used
	@CardinalityMin	xs:nonNegativeInteger or "unbounded"	0 or 1	Minimum number of times this element has to occur
	@CardinalityMax	xs:nonNegativeInteger or "unbounded"	0 or 1	Maximum number of times this element may occur
	@Multilingual	xs:boolean	0 or 1	Indication that the element can have values in multiple languages
	<Documentation>	xs:string	0 to unbounded	Documentation about the purpose of the element
	<AttributeList>	xs:complexType	0 or 1	Additional attributes specified by the component creator
	<ValueScheme>	xs:complexType	0 or 1	Value restrictions based on a regular expression or a specified vocabulary. See Value restrictions for elements and attributes for details.
	<AutoValue>	xs:string	0 to unbounded	Derivation rules for the element's content

CMD attribute definition

Both the CMD element and component description allow the specification of additional CMD attributes. Every CMD attribute definition MUST contain a @name attribute and MAY contain other attributes or elements for a more detailled description.

Name		Valuetype	Occurrences	Description
<Attribute>		xs:complexType		Root element of every CMD attribute definition
	@name	xs:Name	1	Name of the attribute
	@ConceptLink	xs:anyURI	0 or 1	Concept link
	@ValueScheme	Subset of XSD datatypes	0 or 1	Allowed data type if simple XML type is used
	@Required	xs:boolean	0 or 1	Indication if attribute is required
	<Documentation>	xs:string	0 to unbounded	Documentation about the purpose of the attribute
	<ValueScheme>	xs:complexType	0 or 1	Value restrictions based on a regular expression or a specified vocabulary. See Value restrictions for elements and attributes for details.
	<AutoValue>	xs:string	0 to unbounded	Derivation rules for the attribute's content

Value restrictions for elements and attributes

Apart from standard XML schema datatypes the content of a CMD element or attribute instance can be restricted by two means. The <ValueScheme> element MAY contain either an XML element <pattern> with the specification of a regular expression the element/attribute should comply with, or the definition of a controlled vocabulary of allowed values. CMDI 1.2 supports two approaches to describe such a vocabulary:

• specifying all allowed values with OPTIONAL attributes for every value to include a concept link and a description of the specific value, or
• referring to an external vocabulary via a URI specified in @URI. OPTIONAL XML attributes @ValueProperty and @ValueLanguage MAY be used to give more information about preferred label and language in the chosen vocabulary.

Name					Valuetype	Occurrences	Description
<ValueScheme>					xs:complexType		Specification of the value scheme of an element or attribute.
	<pattern>				xs:string	0 or 1	Specification of a regular expression the element/attribute should comply with.
	<Vocabulary>				xs:complexType	0 or 1	Specification of a CMD vocabulary
		<Enumeration>			xs:complexType	0 or 1	Enumeration of items from a controlled vocabulary
			<item>		xs:string	0 to unbounded	An item from a controlled vocabulary
				@ConceptLink	xs:anyURI	0 or 1	Concept link of item value
				@AppInfo	xs:string	0 or 1	End-user guidance about the value of this controlled vocabulary item.
			<appinfo>		xs:string	0 to unbounded	End-user guidance about the value of the controlled vocabulary as a whole. Currently not used.
		@URI			xs:anyURI	0 or 1	URI of an external vocabulary
		@ValueProperty			xs:string	0 or 1	preferred label in the external vocabulary
		@ValueLanguage			xs:language	0 or 1	preferred language in the external vocabulary

Cues attributes

All CMD attribute, element, and component specifications may contain additional attributes with the namespace “​http://www.clarin.eu/cmd/cues/1”. These MAY be used to give information about how the payload contained in the respective part of the CMD instance should be presented. Cues are grouped in component specific styles. Different styles for the same CMD component MAY be developed. The CCSL does not prescribe or suggest a specific set of cue attributes.

Transformation of CCSL into a CMD profile schema definition

A CMD instance document that is serialised as XML according this specification SHOULD contain a reference the location of a CMD profile schema. The infrastructure MUST provide a mechanism to derive such a schema for any specific CMD profile on basis of its definition and that of the CMD components that it references. This section specifies how different aspects of a CMD specification should be transformed into elements of a schema definition. The primary schema language targeted is XML Schema, although the infrastructure MAY provide support for other schema languages, such as DDML or Relax NG. CMD profile schemas SHOULD NOT (MUST NOT?) be derived from CMD specifications that are not CMD profiles.

The transformation as described here is assumed to take place on the fully expanded CMD profile, i.e. a version of the specification that has all referenced (non-inline) CMD Component definitions are resolved and substituted, recursively, by their full definitions.

General properties of the CMD profile schema definition

A CMD profile schema MUST be a single document {or set of linked documents with a single entry point}(?) that allows for the evaluation of a CMD instance on all levels of description defined in one specific CMD profile. The schema MUST require the presence of a CMD instance envelope as described in section "Structure of CMDI-files". The value of the <MdProfile> header item in the CMD instance envelope MUST only be valid if it is equal to the profile id as specified in the associated CMD profile.

The CMD profile schema SHOULD include, as a matter of annotation, a copy of (a subset of) the information contained in the Header section of the CMD profile from which it is derived.

The transformation MAY make use of embedded component identifiers in the CMD component definition to derive (complex) types that can be reused throughout the schema definition.

The schema MUST declare a profile specific payload namespace in addition to the fixed, global namespaces that are used (in particular cmd and cue). This namespace, with RECOMMENDED prefix cmdp, MUST have the following format: http://www.clarin.eu/cmd/1/profiles/{profileId}, where {profileId} refers to the identifier of the profile from which the schema is derived in the Component Registry. All XML elements and XML attributes derived from CMD components, CMD elements and CMD attributes MUST be declared in this namespace.

Interpretation of CMD component definitions in the CCSL

CMD Components which are represented as <Component> XML elements in the CCSL, MUST be realised as XML element declarations with the following property mapping:

Property	XML schema attribute	Derived from	Use
Name of the XML element	@name	@name	REQUIRED
Minimal number of occurrences	@minOccurs	@CardinalityMin, or '1' if XML attribute not present	REQUIRED 1
Maximal number of occurrences	@maxOccurs	@CardinalityMax, or '1' if XML attribute not present	REQUIRED 1
Concept link	@dcr:datcat	@ConceptLink	OPTIONAL
Component id	@cmd:ComponentId	@ComponentId	OPTIONAL

¹The implementation may make use of default evaluation of the schema language if it matches these requirements, as is the case with XML Schema, and therefore omit explicit declaration of these properties

An optional XML Attribute @cmd:ref of type xs:IDREFS MUST be allowed on the XML container element derived from any CMD component.

<Documentation> XML elements contained in CMD Components SHOULD be transformed into documentation elements embedded in the XML element declaration. In these, the content language information contained in the @xml:lang XML attribute SHOULD be preserved.

XML attributes of CMD Components in the 'cue' namespace SHOULD be copied into the XML element declaration, in which case the XML attribute name, namespace and value SHOULD be preserved.

Document structure prescribed by the schema

The first CMD component defined in the CMD profile (the "root component") MUST be mapped as the mandatory, only direct descendant of the <Components> XML element of the CMD instance envelope. CMD components that are defined as direct descendants of another CMD component MUST be mapped as direct descendants of the XML element declaration to which it is transformed. XML components at the CMD component level in the metadata instance MUST be required to be included in the same order as defined in the CMD specification, the first of the resulting XML elements appearing after the last XML element derived from a CMD element at the same level, if present. These descendant CMD Components MUST also be mapped to XML element declarations recursively as described in this specification.

CMD elements MUST be mapped as direct descendants of the XML element declaration derived from the CMD component of which they are direct descendants, and MUST be required to be included in the same order as defined in the CMD specification.

CMD attributes that are defined in the CCSL within <Attribute> XML elements within an <AttributeList> XML element that is a direct descendant of a CMD Component MUST be mapped to XML attribute definitions on the XML container element to which it is transformed.

Interpretation of CMD element definitions in the CCSL

CMD elements, represented as <Element> XML elements in the CCSL, MUST be realised as XML element declarations with the following property mapping:

Property	XML schema attribute	Derived from	Use
Name of the XML element	@name	@name	REQUIRED
Minimal number of occurrences	@minOccurs	@CardinalityMin unless @Multilingual is true, in which case MUST be 'unbounded', or '1' if neither XML attribute is present	REQUIRED 1
Maximal number of occurrences	@maxOccurs	@CardinalityMax, or '1' if XML attribute not present	REQUIRED 1
Type of the XML element	@type	See section 'Content model'
Concept link	@dcr:datcat	@ConceptLink	OPTIONAL
Auto value instruction	@cmd:AutoValue	@AutoValue	OPTIONAL

¹The implementation may make use of default evaluation of the schema language if it matches these requirements, as is the case with XML Schema, and therefore omit explicit declaration of these properties

<Documentation> XML elements contained in CMD elements SHOULD be transformed into documentation elements embedded in the XML element declaration In these, the content language information contained in the @xml:lang XML attribute SHOULD be preserved.

XML attributes of CMD Elements in the 'cue' namespace SHOULD be copied into the XML element declaration, in which case the XML attribute name, namespace and value SHOULD be preserved.

An optional XML Attribute @cmd:ValueConceptLink of type xs:anyURI MUST be allowed on the XML element derived from a CMD element that has a vocabulary with XML attribute @URI defined (see section "Content model for CMD elements and CMD attributes in the schema definition").

The derivation of a content model for the XML element declaration on basis of a CMD element is described below.

Interpretation of CMD attribute definitions in the CCSL

CMD attributes, represented as <Attribute> XML elements in the CCSL, MUST be realised as XML attribute declarations with the following property mapping:

Property	XML schema attribute	Derived from	Use
Name of the XML element	@name	@name	REQUIRED
Use of the XML attribute	@use	'required' if and only if @Required is present and equals true, otherwise 'optional'	REQUIRED 1
Type of the XML attribute	@type	See section 'Content model'
Concept link	@dcr:datcat	@ConceptLink	OPTIONAL
Auto value instruction	@cmd:AutoValue	@AutoValue	OPTIONAL

¹The implementation may make use of default evaluation of the schema language if it matches these requirements, as is the case with XML Schema, and therefore omit explicit declaration of these properties

<Documentation> XML elements contained in CMD attributes SHOULD be transformed into documentation elements embedded in the XML attribute declaration In these, the content language information contained in the @xml:lang XML attribute SHOULD be preserved.

XML attributes of CMD Attributes in the 'cue' namespace SHOULD be copied into the XML attribute declaration, in which case the XML attribute name, namespace and value SHOULD be preserved.

The derivation of a content model for the XML attribute declaration on basis of a CMD attribute is described below.

Content model for CMD elements and CMD attributes in the schema definition

If a CMD element or CMD attribute in the CCSL has a @ValueScheme XML attribute, its value MUST be interpreted as the name of the XML Schema Datatype (declared in the @type attribute of the XML element or attribute declaration in XML Schema) that defines the allowed value range of the XML element/attribute derived from the CMD element/attribute.

Otherwise, if a CMD element or CMD attribute in the CCSL has a descendant XML element <ValueScheme> that contains an XML element <pattern>, then its text value MUST be interpreted as the XML Schema Regular Expressions that defines the allowed value range of the XML element/attribute derived from this CMD element/attribute.

Otherwise, if a CMD element or CMD attribute in the CCSL has a descendant XML element <ValueScheme> that contains an XML element <Vocabulary>:

• The XML attribute @URI of the XML element <Vocabulary>, if present, SHOULD be transformed into an attribute cmd:Vocabulary¹ of the same value on the XML element or attribute declaration in the schema.
• The XML attributes @ValueProperty and @ValueLanguage of the XML element <Vocabulary> SHOULD be transformed into XML attributes¹ in the 'cmd:' namespace on the XML element declaration in the case of a CMD element or XML attribute declaration in the case of a CMD attribute.
• The XML elements <item> that are descendants of <enumeration> contained in <Vocabulary> MUST be transformed into an enumeration based restriction with values taken from the text content of the <item> XML elements. Each enumeration item in the schema SHOULD be annotated the value from the XML attribute @ConceptLink by means of an XML attribute @dcr:datcat¹ and the value of the XML attribute @AppInfo by means of an attribute @cmd:label.

¹The attributes @cmd:Vocabulary, @cmd:ValueProperty, @cmd:ValueLanguage and @dcr:datcat should be present in the schema, not be declared as attributes allowed in the CMD instance

Appendices

Bibliography

IETF RFC 2045, Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies

IETF RFC 2046, Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types

IETF RFC 5646, Tags for Identifying Languages

ISO 639‐1, Codes for the representation of names of languages — Part 1: Alpha-2 code

ISO 639‐3, Codes for the representation of names of languages -- Part 3: Alpha-3 code for comprehensive coverage of languages

ISO 3166‐1, Codes for the representation of names of countries and their subdivisions — Part 1: Country codes

ISO 8601, Data elements and interchange formats — Information interchange — Representation of dates and times

ISO/IEC 10646‐1, Information technology — Universal Multiple-Octet Coded Character Set (UCS) — Part 1: Architecture and Basic Multilingual Plane XML Schema Part 2: Datatypes, Biron, P.V. and Malhotra, A. (eds.), W3C Recommendation 02 May 2001, available at <​http://www.w3.org/TR/xmlschema-2/>