File: uri_keyword_20080803a.txt

It is proposed to register the following new text keyword for
use in PNG files:

URI An absolute URI (Uniform Resource Identifier) related to the image.
    The URI may be accompanied by a text explaining the relationship.
    Decoders that recognize this keyword should be capable to extract
    the URI out of the surrounding free-form text, using the absolute URI
    syntax defined in [RFC 3986|http://tools.ietf.org/html/rfc3986]