Binary Data in XML

John Cowan cowan at
Wed Sep 30 18:51:06 BST 1998

Tim Bray scripsit:

> Suppose I wrote up a NOTE, should occupy less than one page, proposing
> a reserved attribute xml:packed with, for the moment, only two
> allowed values, "none" and "base64".  The default value is "none".
> If an element has xml:packed="base64" this means that
> (a) the content of the element to which this is attached must be
>     pure #PCDATA, no child elements and no references, and
> (b) the content is encoded in base64, leading and trailing spaces allowed

Excellent.  I have the following suggestions:

1) Any S characters should be allowed in base64 content, but ignored.
That agrees with the normal use of Base64, where line end characters
are typically added every 64 characters or so.

2) xml:packed should be a notation attribute, and W3C should define
a public ID for Base 64 notation, based on RFC 2045.

3) It should be pointed out that this is a typical example of
notation-governed elements.  At the moment, the use of notation
attributes in XML is not well motivated by the Recommendation.

John Cowan		cowan at
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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