Copyright IPR Systems 2001. Distribution policies are governed by the W3C intellectual property terms.
This note specifies a Resource Description Framework (RDF) encoding of the vCard profile defined by RFC 2426 and to provide equivalent functionality to its standard format. The motivation is to enable the common and consistent description of persons (using the existing semantics of vCard) and to encode these in RDF/XML.
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This note specifies a Resource Description Framework (RDF) [RDF] expression that corresponds to the vCard electronic business card profile defined by RFC 2426 [VCARD]. This specification provides equivalent functionality to the standard format defined by [VCARD] Version 3.0. RDF is an application of the Extensible Markup Language [XML]. Documents structured in accordance with this RDF/XML encoding may also be known as 'RDF vCard' documents.
This specification is in no way intended to create a separate definition for the vCard schema. The sole purpose for this note is to define an alternative RDF/XML encoding for the format defined by [VCARD].
The RDF vCard does not introduce any capability not expressible in the format defined by [VCARD]. However, an attempt has been made to leverage the capabilities of the XML and RDF syntax to better articulate the original intent of the vCard authors.
RDF uses the XML Namespace [XMLNS] to uniquely identify the metadata schema and version. For vCard, the following URI [URI] is defined to be vCard Namespace:
The explicit use of this XML Namespace in RDF means that there is no need to support the VCARD Profile and VERSION type.
This namespace name (URI) will only be used to refer to this version of this specification: different URIs will be used for any and all new versions of the specification except as follows.
Examples used in this note will use "vCard" as the prefix for the vCard XML Namespace and "rdf" for the RDF XML Namespace.
The RDF vCard equally promotes all vCard types into RDF property types. Some of the vCard types, for example BEGIN, END, PROFILE, and VERSION, are not required to be expressed as these are implicitly provided by RDF.
With RDF, statements are made about a resource. The resource in question is identified with a URI. This has similar semantics to the vCard UID type. Hence, RDF descriptions should use the vCard UID as the RDF "about" value when the UID is expressed as a machine-resolvable URI.
The majority of the vCard property types have strings as their values (objects of statements) and are simply represented by their property type name and value as specified in the vCard specification [VCARD]. These include:
For example, the following shows sample RDF vCard encodings:
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:BDAY> 1980-01-01 </vCard:BDAY>
<vCard:TITLE> Computer Officer Class 3 </vCard:TITLE>
<vCard:ROLE> Programmer </vCard:ROLE>
There are special cases to be noted for the SOURCE and NAME property types. SOURCE maps to the RDF "about" URI and should be used to indicate the unique identifier for the person object. NAME is a human-displayable text about the vCard record itself (not the person). If NAME is required, then it should be represented as a Statement about Statements (see Section 4 of the RDF Syntax specification [RDF].)
To have multiple values of a vCard property type, RDF provides three mechanisms; Bags, Sequences, and Alternatives.
An RDF Bag is used when there is more than one value and the order is not important. For example:
<vCard:ROLE> <rdf:bag>
<rdf:li> Programmer </rdf:li>
<rdf:li> Fire Warden </rdf:li>
</rdf:bag>
</vCard:ROLE>
If order is important, then an RDF Sequence can be used. For example:
<vCard:TITLE> <rdf:seq>
<rdf:li> Principal Research Scientist </rdf:li>
<rdf:li> Visiting Professor </rdf:li>
</rdf:seq>
</vCard:TITLE>
An RDF Alternative is used when there is a choice of values available for a property, with each value being valid but dependent on some other externally defined factor. The first value is the default. For example, a vCard resource may have a number of aliases for their email address. In essence, these are all different representations of the same email addresses. This would be encoded as:
<vCard:EMAIL> <rdf:alt>
<rdf:li> corky@qqqfoo.com </rdf:li>
<rdf:li> info@qqqfoo.com </rdf:li>
<rdf:li> corky2000cool@hotmail.com </rdf:li>
</rdf:alt>
</vCard:EMAIL>
The vCard specification also allows properties to be arbitrarily grouped. For RDF to support this, we need to define a new vCard property to capture this. We call this new vCard property "GROUP".
For example, to group two NICKNAME and NOTE properties:
<vCard:GROUP>
<rdf:bag>
<rdf:li rdf:parseType="Resource">
<vCard:NICKNAME> Corky Porky </vCard:NICKNAME>
<vCard:NOTE> Only used by close friends </vCard:NOTE>
</rdf:li> <rdf:li rdf:parseType="Resource">
<vCard:NICKNAME> Princess Corky </vCard:NICKNAME>
<vCard:NOTE> Only used by my Mother </vCard:NOTE>
</rdf:li>
</rdf:bag>
</vCard:GROUP>
Note: The "rdf:parseType=Resource" indicates that the <rdf:li> content should be treated as if it were the content of an <rdf:Description> element.
Some of these grouping and ordering features are unique to RDF, so it is important to realise that the conversion from RDF to native vCard format may result in some loss of information. However, it should not be a critical loss of semantics.
A number of vCard properties include the ability to indicate one or more "type parameters" of a value. For example, to indicate that a Telephone number is a Fax number, or that a particular email address is the preferred value.
To represent this in RDF, we utilise the <rdf:type> property which allows us to specify the type of a resource by indicating a URI that represents this type. The URI will be:
where <type> will be one of the officially defined vCard type parameters.
Also, the property value must now be given by using the <rdf:value> property. For example:
<vCard:TEL rdf:parseType="Resource">
<rdf:value> +61 7 555 5555 </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#work"/>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#voice"/>
</vCard:TEL>
Note: The "rdf:parseType=Resource" simply indicates properties within the two <vCard:Tel> tags, should be considered as the entire value for the <vCard:Tel> property.
The vCard properties that have a type parameter are listed here with their possible values:
vCard Property Type Parameter Values
-------------- -----------------------------------------------
TEL home, msg, work, pref, voice, fax, cell, video,
pager, bbs, modem, car, isdn, pcs
EMAIL internet, x400, pref
ADR dom, intl, postal, parcel, home, work, pref
LABEL dom, intl, postal, parcel, home, work, pref
TZ text
In cases where the type parameter has been defined by an external body (ie: not defined by the vCard specification), we must use a "vCard:TYPE" attribute in the property since we have no control over the potential size of this list.
For example, to indicate that the value for the UID property is of type "United States Social Security Number":
<vCard:UID vCard:TYPE="US-SSN">
987-65-4320
</vCard:UID>
The vCard properties that have uncontrolled type parameters are listed here:
vCard Property Type Parameter Values
-------------- -----------------------------------------------
UID Any IANA registered or non-standard identifier formats
LOGO Any IANA registered or non-standard image formats
PHOTO Any IANA registered or non-standard image formats
SOUND Any IANA registered or non-standard audio formats
There are two special cases to be noted:
<vCard:URL rdf:resource="http://qqqfoo.com/me.html"/>
<vCard:LABEL rdf:parseType="Resource">
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#postal"/>
<rdf:value rdf:parseType="Literal">
Corky Crystal<br/>
<b>qqqfoo.com Pty Ltd</b><br/>
PO Box 555<br/>
Coolville, AUSTRALIA
</rdf:value>
</vCard:LABEL>
A number of vCard properties define sub-structure. For example, the N property has Family Name, Given Names, and Honorific. It is important to preserve and express this structure and it is fully-supported in the RDF model. For example:
<vCard:N rdf:parseType="Resource">
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
<vCard:Other> Jacky </vCard:Other>
<vCard:Prefix> Dr </vCard:Prefix>
<vCard:Suffix> III </vCard:Suffix>
</vCard:N>
The properties that have defined sub-structure are listed here with the names of the property types.
vCard Property Substructure Name Property Type Name
-------------- -------------------- ------------------
N Family Name Family
Given Name Given
Additional Names Other
Honorific Prefixes Prefix
Honorific Suffixes Suffix
ADR Post Office Box Pobox
Extended Address Extadd
Street Address Street
Locality Locality
Region Region
Postal Code Pcode
Country Country
ORG Organisation Name Orgname
Organisation Unit Orgunit
There are two special cases to be noted:
A number of vCard properties allow for inline binary values (encoded in BASE64) or external references via a URI. These include:
In the case of binary values, we can represent the property with a "vCard:ENCODING" attribute indicating the content value ("b"). For example:
<vCard:PHOTO vCard:ENCODING="b" vCard:TYPE="image/jpeg">
MSJD9s99DS(S@W99329(#9....
</vCard:PHOTO>
In the case of an external reference, RDF provides a convenient encoding with the "rdf:resource" construct. For example:
<vCard:PHOTO vCard:TYPE="image/gif"
rdf:resource="http://qqqfoo.com/me.gif"/>
The Agent property allows the specification or identification of another vCard resource. RDF allows for the Agent vCard resource to be inline with an existing vCard resource. For example:
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:TITLE> Research Director </vCard:TITLE>
<vCard:AGENT rdf:parseType="Resource">
<vCard:FN> John Mutton </vCard:FN>
<vCard:TITLE> Personal Assistant </vCard:TITLE>
<vCard:EMAIL> john@qqqfoo.com </vCard:EMAIL>
</vCard:AGENT>
To refer to an external identifiers (via a URI) of the Agent resource, RDF supports encoding with the "rdf:resource" construct. For example:
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:TITLE> Research Director </vCard:TITLE>
<vCard:AGENT rdf:resource="http://qqqfoo.com/staff/mutton/"/>
To express the human language encoding of vCard property values, XML provides a convenient "xml:lang" attribute. The values are defined in RFC 1766. For example:
<vCard:FN xml:lang="en"> Corky Crystal </vCard:FN>
<vCard:TITLE xml:lang="en"> Computer Officer Class 3 </vCard:TITLE>
<vCard:ROLE xml:lang="en"> Programmer </vCard:ROLE>
In cases where a single vCard property is expressed with multiple language values, the RDF Alternative construct should be used. For example:
<vCard:ROLE> <rdf:alt>
<rdf:li xml:lang="en"> Programmer </rdf:li>
<rdf:li xml:lang="fr"> Programmeur </rdf:li>
<rdf:li xml:lang="it"> Programmatore </rdf:li>
</rdf:alt>
</vCard:ROLE>
It is important to note that since XML is case-sensitive, the property and attribute names used in this specification and the below examples, should be taken literally.
The following is a complete example of an RDF encoded vCard:
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:vCard = "http://www.w3.org/2001/vcard-rdf/3.0#">
<rdf:Description rdf:about = "http://qqqfoo.com/staff/corky" >
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:N rdf:parseType="Resource">
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
<vCard:Other> Jacky </vCard:Other>
<vCard:Prefix> Dr </vCard:Prefix>
</vCard:N>
<vCard:BDAY> 1980-01-01 </vCard:BDAY>
<vCard:TITLE> Computer Officer Class 3 </vCard:TITLE>
<vCard:ROLE> Programmer </vCard:ROLE>
<vCard:TEL rdf:parseType="Resource">
<rdf:value> +61 7 555 5555 </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#work"/>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#voice"/>
</vCard:TEL>
<vCard:EMAIL rdf:parseType="Resource">
<rdf:value> corky@qqqfoo.com </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#internet"/>
</vCard:EMAIL>
<vCard:ADR rdf:parseType="Resource">
<vCard:Street> 111 Lake Drive </vCard:Street>
<vCard:Locality> WonderCity </vCard:Locality>
<vCard:Pcode> 5555 </vCard:Pcode>
<vCard:Country> Australia </vCard:Country>
</vCard:ADR>
</rdf:Description>
</rdf:RDF>
The following is an example of an RDF vCard that includes a photo element as inline binary content.
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:vCard = "http://www.w3.org/2001/vcard-rdf/3.0#" >
<rdf:Description rdf:about = "http://qqqfoo.com/staff/corky">
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:N rdf:parseType="Resource">
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
</vCard:N>
<vCard:EMAIL rdf:parseType="Resource">
<rdf:value> corky@qqqfoo.com </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#internet"/>
</vCard:EMAIL>
<vCard:URL rdf:resource="http://qqqfoo.com/staff/corky-home.html"/>
<vCard:PHOTO vCard:ENCODING="b" vCard:TYPE="image/jpeg">
MIICajCCAdOgAwIBAgICBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDA
qBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25z.....W992WW329
</vCard:PHOTO>
</rdf:Description>
</rdf:RDF>
This example shows how an RDF vCard objects can be integrated with other metadata standards and encoded with RDF. In this example, the Dublin Core Metadata Element Set [DCMES] standard is used. (Please refer to [DCMES] for namespace and encoding recommendations.)
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:DC = "http://purl.org/dc/elements/1.1/"
xmlns:vCard = "http://www.w3.org/2001/vcard-rdf/3.0#" >
<rdf:Description rdf:about = "http://qqqfoo.com/annual-report.html" >
<DC:title> Annual Report 1999/2000 </DC:title>
<DC:creator rdf:parseType="Resource">
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:N rdf:parseType="Resource">
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
</vCard:N>
<vCard:EMAIL rdf:parseType="Resource">
<rdf:value> corky@qqqfoo.com </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#internet"/>
</vCard:EMAIL>
</DC:creator>
<DC:date> 2000-10-01 </DC:date>
<DC:subject> Company Report, Outcomes, Objectives </DC:subject>
<DC:publisher> qqqfoo.com Pty Ltd </DC:publisher>
<DC:rights> Copyright 2000 </DC:rights>
</rdf:Description>
</rdf:RDF>
The following is an example of an RDF vCard that includes structured Organisation information:
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:vCard = "http://www.w3.org/2001/vcard-rdf/3.0#" >
<rdf:Description rdf:about = "http://qqqfoo.com/staff/corky">
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:N rdf:parseType="Resource">
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
</vCard:N>
<vCard:EMAIL rdf:parseType="Resource">
<rdf:value> corky@qqqfoo.com </rdf:value>
<rdf:type rdf:resource="http://www.w3.org/2001/vcard-rdf/3.0#internet"/>
</vCard:EMAIL>
<vCard:ORG rdf:parseType="Resource">
<vCard:Orgname> qqqfoo.com Pty Ltd </vCard:Orgname>
<vCard:Orgunit>
<rdf:seq>
<rdf:li> Commercialisation Division </rdf:li>
<rdf:li> Engineering Office </rdf:li>
<rdf:li> Java Unit </rdf:li>
</rdf:seq>
</vCard:Orgunit>
</vCard:ORG>
</rdf:Description>
</rdf:RDF>
It is also possible to encode vCard in XML without the RDF expressions (although this is out of scope for this note). This would enable XML expressions to be generated without the need to support RDF. However, there will be some features then lacking and unable to be represented in standard XML.
For example, the following is a standard XML expression of last example in the previous section:
<?xml version="1.0"?>
<myns:myElement xmlns:myns = "http://www.qqqfoo.com/my-namespace#"
xmlns:vCard = "http://www.w3.org/2001/vcard-rdf/3.0#" >
<vCard:FN> Corky Crystal </vCard:FN>
<vCard:N>
<vCard:Family> Crystal </vCard:Family>
<vCard:Given> Corky </vCard:Given>
</vCard:N>
<vCard:EMAIL vcard:TYPE="http://www.w3.org/2001/vcard-rdf/3.0#internet">
corky@qqqfoo.com </vCard:EMAIL>
<vCard:ORG>
<vCard:Orgname> qqqfoo.com Pty Ltd </vCard:Orgname>
<vCard:Orgunit> Commercialisation Division </vCard:Orgunit>
<vCard:Orgunit> Engineering Office </vCard:Orgunit>
<vCard:Orgunit> Java Unit </vCard:Orgunit>
</vCard:ORG>
</myns:myElement >
Note that all of the RDF grouping mechanisms and attributes can no longer be used. The vCard:TYPE attribute (only one) can be used for all vCard attributes/types.
Thanks to Dave Beckett (Uni Kent), Roland Schwaenzl (Uni Osnabrueck), Ron Daniel (DATAFUSION), Eric Miller (OCLC), and Hoylen Sue (DSTC) for their valuable feedback and comments on drafts of this document.
Early versions of the work reported in this paper has been funded in part by the Cooperative Research Centres Program through the Department of the Prime Minister and Cabinet of Australia, whilst the Author was an employee of DSTC.