Internet Engineering Task Force (IETF) R. Stepanek Request for Comments: 9982 Fastmail Updates: 9555 May 2026 Category: Standards Track ISSN: 2070-1721 JSContact Version 2.0: A JSON Representation of Contact Data Abstract This document defines version "2.0" of JSContact. It defines the uid property of a Card object to be optional, rather than mandatory, as defined previously in version "1.0". All other definitions of JSContact version "1.0" remain as defined in RFC 9553. This document updates RFC 9555 by redefining how to convert the now optional uid property from and to vCard. It also registers the vCard JSCOMPS parameter at IANA, which was defined but not registered in RFC 9555. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9982. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction 2. Notational Conventions 3. JSContact Version 2.0 4. Redefined uid Property 5. Redefined Conversion Rule for the uid Property 6. Other Changes 7. IANA Considerations 7.1. Update to the JSContact Version Registry 7.2. Update to the JSContact Properties Registry 7.3. Update to the vCard Parameters Registry 8. Security Considerations 9. References 9.1. Normative References 9.2. Informative References Author's Address 1. Introduction JSContact [RFC9553] defines the Card object uid property, a mandatory property that contains a unique identifier for the entity represented by that contact card. For the same purpose, the vCard [RFC6350] contact format defines the UID property, an optional property of a vCard instance. Throughout the rest of this document, the term uid (all lowercase) denotes the JSContact uid property, and the term UID (all uppercase) denotes the vCard UID property. The uid property being defined as mandatory in JSContact has shown to be applicable for some use cases but turned out to be an issue in other contexts. For example, the CardDAV protocol [RFC6352] requires the UID property of a vCard object [RFC6350] to be set. Accordingly, an internet server that implements both CardDAV and JSON Meta Application Protocol (JMAP) for Contacts [RFC9610] requires the uid property of a JSContact Card to be set. In contrast, protocols such as Registration Data Access Protocol (RDAP) [RFC9083] have no use for the uid property, either because they use different identifiers or they prefer to not include any unique identifier in the contact data at all. JSContact should not require them to generate unique identifiers that are irrelevant to their use case. Also, one of the stated goals of JSContact is to be compatible with the semantics of the vCard data format (Section 1 of [RFC9553]). But [RFC6350] defines the UID property of a vCard to be optional, and consequently, the semantics of JSContact and vCard differ for such a crucial common element. In case of vCards without a UID property (Section 6.7.6 of [RFC6350]) being converted to JSContact, requiring unique identifiers is especially problematic: The Card uid property is mandatory, and accordingly, Section 2.1.1 of [RFC9555] requires implementations to generate some unique identifier for it during conversion, but it does not guarantee it to be the same across implementations or even one implementation converting the same Card multiple times. A recipient being unaware that the uid property value of such a Card object is ephemeral might refer to it in the members property or relatedTo property of another Card object, introducing invalid relations between contact cards. 2. Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. The ABNF definitions in this document use the notations of [RFC5234]. ABNF rules not defined in this document are defined in either [RFC5234] (such as the ABNF for CRLF, WSP, DQUOTE, VCHAR, ALPHA, and DIGIT) or [RFC6350]. 3. JSContact Version 2.0 This document redefines the uid property of a Card object to become optional. Other than that, the property definition is left unchanged. This change requires the major version of JSContact to change, so this document defines the JSContact version to become "2.0". For further information about versioning JSContact data, see Section 1.9 of [RFC9553]. Implementations MUST create JSContact data that complies with the definitions of version "2.0" (or some later registered version) and MUST set the version property of the JSContact Card object to that version. They MUST NOT reject a Card object without the uid property as invalid unless specified differently in another document or unless the Card version property has value "1.0". As any valid version "1.0" JSContact Card is also valid according to version "2.0", there is no need to migrate existing JSContact data. Setting the uid property is use case specific. If an implementation is able to consistently generate the exact same unique identifier for a JSContact Card representing the same entity and no protocol- specific concerns prevail, it is recommended to set the uid property. This document does not redefine the vCard UID property. 4. Redefined uid Property This document redefines the type signature of the uid property, originally defined in Section 2.1.9 of [RFC9553]. OLD: | *uid: String (mandatory).* NEW: | *uid: String (optional).* The remaining property definition is left unchanged, with the following additional paragraph: | A Card without an uid property cannot be referred to as a group | member in the members property (Section 2.1.6 of [RFC9553]) or put | in relation to another Card object in the relatedTo property | (Section 2.1.8 of [RFC9553]). 5. Redefined Conversion Rule for the uid Property This document redefines how to convert the Card uid property from vCard, originally defined in Section 2.1.1 of [RFC9555]. The new conversion rule is as follows: Implementations that convert a vCard without a UID property (Section 6.7.6 of [RFC6350]) to a Card of version "2.0" or higher MUST NOT generate a unique identifier as a value for the uid property (Section 2.1.9 of [RFC9553]). When converting a vCard without a UID property to JSContact version "1.0", implementations MUST generate a value for the uid property. Generating unique identifiers is implementation specific. An implementation SHOULD generate the same value when generating the same Card multiple times. Section 1 describes why this is problematic. Consequently, implementations SHOULD NOT convert to version "1.0" Card objects. 6. Other Changes This document also registers the JSCOMPS parameter in the IANA "vCard Parameters" registry. The parameter was defined in Section 3.3.1 of [RFC9555] but mistakenly not registered at IANA. 7. IANA Considerations 7.1. Update to the JSContact Version Registry IANA has updated the "JSContact Version" registry, originally created in Section 3.4 of [RFC9553], by adding the following record: +===============+=======================+===========+ | Major Version | Highest Minor Version | Reference | +===============+=======================+===========+ | 2 | 0 | RFC 9982 | +---------------+-----------------------+-----------+ Table 1: JSContact Version Registry 7.2. Update to the JSContact Properties Registry IANA has updated the "JSContact Properties" registry, originally created in Section 3.5 of [RFC9553]: In the "Reference/Description" column of the uid property, a reference to Section 4 of this document has been added. 7.3. Update to the vCard Parameters Registry IANA has updated the "vCard Parameters" registry within the "vCard Elements" registry group by adding the following entry: +===========+===========+============================+ | Namespace | Parameter | Reference | +===========+===========+============================+ | | JSCOMPS | Section 3.3.1 of [RFC9555] | +-----------+-----------+----------------------------+ Table 2: vCard Parameters Registry 8. Security Considerations This document does not provide new security considerations. The security considerations of Section 4 of [RFC9553] apply. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, . [RFC6350] Perreault, S., "vCard Format Specification", RFC 6350, DOI 10.17487/RFC6350, August 2011, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC9553] Stepanek, R. and M. Loffredo, "JSContact: A JSON Representation of Contact Data", RFC 9553, DOI 10.17487/RFC9553, May 2024, . [RFC9555] Loffredo, M. and R. Stepanek, "JSContact: Converting from and to vCard", RFC 9555, DOI 10.17487/RFC9555, May 2024, . 9.2. Informative References [RFC6352] Daboo, C., "CardDAV: vCard Extensions to Web Distributed Authoring and Versioning (WebDAV)", RFC 6352, DOI 10.17487/RFC6352, August 2011, . [RFC9083] Hollenbeck, S. and A. Newton, "JSON Responses for the Registration Data Access Protocol (RDAP)", STD 95, RFC 9083, DOI 10.17487/RFC9083, June 2021, . [RFC9610] Jenkins, N., Ed., "JSON Meta Application Protocol (JMAP) for Contacts", RFC 9610, DOI 10.17487/RFC9610, December 2024, . Author's Address Robert Stepanek Fastmail PO Box 234 Collins St. West Melbourne VIC 8007 Australia Email: rsto@fastmailteam.com