RFC 2397 (rfc2397) - Page 1 of 5

The "data" URL scheme

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Network Working Group                                      L. Masinter
Request for Comments: 2397                           Xerox Corporation
Category: Standards Track                                  August 1998


                         The "data" URL scheme

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

1. Abstract

   A new URL scheme, "data", is defined. It allows inclusion of small
   data items as "immediate" data, as if it had been included
   externally.

2. Description

   Some applications that use URLs also have a need to embed (small)
   media type data directly inline. This document defines a new URL
   scheme that would work like 'immediate addressing'. The URLs are of
   the form:

                    data:[][;base64],

   The  is an Internet media type specification (with
   optional parameters.) The appearance of ";base64" means that the data
   is encoded as base64. Without ";base64", the data (as a sequence of
   octets) is represented using ASCII encoding for octets inside the
   range of safe URL characters and using the standard %xx hex encoding
   of URLs for octets outside that range.  If  is omitted, it
   defaults to text/plain;charset=US-ASCII.  As a shorthand,
   "text/plain" can be omitted but the charset parameter supplied.

   The "data:" URL scheme is only useful for short values. Note that
   some applications that use URLs may impose a length limit; for
   example, URLs embedded within  anchors in HTML have a length limit
   determined by the SGML declaration for HTML [RFC 1866]. The LITLEN
   (1024) limits the number of characters which can appear in a single



Masinter                    Standards Track
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