URL-encode fragment identifier?

[Christian Roth]

Hi,

having searched the net for answers, I have found both points of view,
namely that fragment identifiers need to be URL-encoded - or that they
must not.

Is there some definitive resource or settled consensus as to whether the
fragment identifier part of a URL must be URL encoded (i.e. certain
characters outside the ASCII range be escaped using '%HH') or that they
mustn't?

I am asking specifically for XML documents supporting XLink, so as an
example, how does an internal link to this element (id being of type
ID):

<anchor id="X&auml;X" />

need to be encoded to be compatible with XLink compatible, XML
supporting processing systems, form (a) or form (b):

(a) <ref xlink:href="#X&auml;X" />
(b) <ref xlink:href="#X%E4X" />


Regards, Christian.