Guidelines for new URL Schemes (RFC2718)
Original Publication Date: 1999-Nov-01
Included in the Prior Art Database: 2019-Feb-10
Internet Society Requests For Comment (RFCs)
L. Masinter: AUTHOR [+3]
This document provides guidelines for the definition of new URL schemes. This memo provides information for the Internet community.
Network Working Group L. Masinter Request for Comments: 2718 Xerox Corporation Category: Informational H. Alvestrand Maxware, Pirsenteret D. Zigmond WebTV Networks, Inc. R. Petke UUNET Technologies November 1999
Guidelines for new URL Schemes
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 (C) The Internet Society (1999). All Rights Reserved.
A Uniform Resource Locator (URL) is a compact string representation of the location for a resource that is available via the Internet. This document provides guidelines for the definition of new URL schemes.
A Uniform Resource Locator (URL) is a compact string representation of the location for a resource that is available via the Internet. RFC 2396  defines the general syntax and semantics of URIs, and, by inclusion, URLs. URLs are designated by including a "<scheme>:" and then a "<scheme-specific-part>". Many URL schemes are already defined.
This document provides guidelines for the definition of new URL schemes, for consideration by those who are defining and registering or evaluating those definitions.
The process by which new URL schemes are registered is defined in RFC 2717 .
Masinter, et al. Informational [Page 1]
RFC 2718 Guidelines for new URL Schemes November 1999
2. Guidelines for new URL schemes
Because new URL schemes potentially complicate client software, new schemes must have demonstrable utility and operability, as well as compatibility with existing URL schemes. This section elaborates these criteria.
2.1 Syntactic compatibility
New URL schemes should follow the same syntactic conventions of existing schemes when appropriate. If a URI scheme that has embedded links in content accessed by that scheme does not share syntax with a different scheme, the same content cannot be served up under different schemes without rewriting the content. This can already be a problem, and with future digital signature schemes, rewriting may not even be possible. Deployment of other schemes in the future could therefore become extremely difficult.
2.1.1 Motivations for syntactic compatibility
Why should new URL schemes share as much of the generic URI syntax (that makes sense to share) as possible? Consider the following:
o If fragment syntax isn’t shared between two schemes, (e.g. "<a href="#foo">"), you can’t move individual completely self referential documents between schemes without rewriting the embedded references within the document. In the Web, the fragment syntax is a property of the media type, and evaluated by the client.
o If fragment syntax is not shared between different media types of the same capability (e.g. HTML, XML, Word, or image types such as GIF, JPEG, PNG) then you can’t have a URI reference that can evolve to superior media types as they become available, or even likely work properly today with conten...