Encoding URI's for xml validation

Should this be allowed...The use of the %3A to encode
the reserved character ':' as shown below?

<!DOCTYPE AAF SYSTEM "file:///e%3a/test/out.dtd">
to substitue for

<!DOCTYPE AAF SYSTEM "file:///e:/test/out.dtd">

when validating the xml against the dtd mentioned
above.

IE doesn't like this and neither does some tools I've
tested this with and I am in disagreement with someone
on whether or not this is allowed. Any help or advice
would be ideal
RFC 2396 doesn't seem to give me an answer



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