The 'tag' URI Scheme
RFC 4151
Document | Type |
RFC - Informational
(October 2005; Errata)
Was draft-kindberg-tag-uri (individual in app area)
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Authors | Sandro Hawke , Tim Kindberg | ||
Last updated | 2020-01-21 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4151 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Ted Hardie | ||
Send notices to | (None) |
Network Working Group T. Kindberg Request for Comments: 4151 Hewlett-Packard Corporation Category: Informational S. Hawke World Wide Web Consortium October 2005 The 'tag' URI Scheme Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Disclaimer The views and opinions of authors expressed herein do not necessarily state or reflect those of the World Wide Web Consortium, and may not be used for advertising or product endorsement purposes. This proposal has not undergone technical review within the Consortium and must not be construed as a Consortium recommendation. Abstract This document describes the "tag" Uniform Resource Identifier (URI) scheme. Tag URIs (also known as "tags") are designed to be unique across space and time while being tractable to humans. They are distinct from most other URIs in that they have no authoritative resolution mechanism. A tag may be used purely as an entity identifier. Furthermore, using tags has some advantages over the common practice of using "http" URIs as identifiers for non-HTTP-accessible resources. Kindberg & Hawke Informational [Page 1] RFC 4151 Tag URIs October 2005 Table of Contents 1. Introduction ....................................................2 1.1. Terminology ................................................3 1.2. Further Information and Discussion of this Document ........4 2. Tag Syntax and Rules ............................................4 2.1. Tag Syntax and Examples ....................................4 2.2. Rules for Minting Tags .....................................5 2.3. Resolution of Tags .........................................7 2.4. Equality of Tags ...........................................7 3. Security Considerations .........................................7 4. IANA Considerations .............................................8 5. References ......................................................9 5.1. Normative References .......................................9 5.2. Informative References .....................................9 1. Introduction A tag is a type of Uniform Resource Identifier (URI) [1] designed to meet the following requirements: 1. Identifiers are likely to be unique across space and time, and come from a practically inexhaustible supply. 2. Identifiers are relatively convenient for humans to mint (create), read, type, remember etc. 3. No central registration is necessary, at least for holders of domain names or email addresses; and there is negligible cost to mint each new identifier. 4. The identifiers are independent of any particular resolution scheme. For example, the above requirements may apply in the case of a user who wants to place identifiers on their documents: a. The user wants to be reasonably sure that the identifier is unique. Global uniqueness is valuable because it prevents identifiers from becoming unintentionally ambiguous. b. The identifiers should be tractable to the user, who should, for example, be able to mint new identifiers conveniently, to memorise them, and to type them into emails and forms. c. The user does not want to have to communicate with anyone else in order to mint identifiers for their documents. Kindberg & Hawke Informational [Page 2] RFC 4151 Tag URIs October 2005 d. The user wants to avoid identifiers that might be taken to imply the existence of an electronic resource accessible via a default resolution mechanism, when no such electronic resource exists. Existing identification schemes satisfy some, but not all, of the requirements above. For example: UUIDs [5], [6] are hard for humans to read. OIDs [7], [8] and Digital Object Identifiers [9] require entities to register as naming authorities, even in cases where the entity already holds a domain name registration. URLs (in particular, "http" URLs) are sometimes used as identifiers that satisfy most of the above requirements. Many users and organisations have already registered a domain name, and the use of the domain name to mint identifiers comes at no additional cost. But there are drawbacks to URLs-as-identifiers: o An attempt may be made to resolve a URL-as-identifier, even thoughShow full document text