www.stack.nl/~dimitri/doxygen started to return "403 Forbidden" a while ago. Let's hope that www.doxygen.nl stays in place for a while now; it's getting a little annoying chase those Doxygen URLs.
On the way I rewrote one reference to avoid a "here" link, which are recommended against from a usability perspective (and also do not help search engines). Committed. Gerald 2019-07-28 Gerald Pfeifer <ger...@pfeifer.com> * doc/xml/manual/documentation_hacking.xml: Fix broken reference to the Doxygen manual. Avoid a "here" link on the way. Fix another broken link to Doxygen docblocks. Index: doc/xml/manual/documentation_hacking.xml =================================================================== --- doc/xml/manual/documentation_hacking.xml (revision 273851) +++ doc/xml/manual/documentation_hacking.xml (working copy) @@ -445,9 +445,10 @@ <para> Adding Doxygen markup to a file (informally called - <quote>doxygenating</quote>) is very simple. The Doxygen manual can be - found - <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.stack.nl/~dimitri/doxygen/download.html#latestman">here</link>. + <quote>doxygenating</quote>) is very simple. See the + <link xmlns:xlink="http://www.w3.org/1999/xlink" + xlink:href="http://www.doxygen.nl/download.html#latestman">Doxygen + manual</link> for details. We try to use a very-recent version of Doxygen. </para> @@ -463,7 +464,8 @@ <para> Some commentary to accompany - the first list in the <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.stack.nl/~dimitri/doxygen/manual/docblocks.html">Special + the first list in the <link xmlns:xlink="http://www.w3.org/1999/xlink" + xlink:href="http://www.doxygen.nl/manual/docblocks.html">Special Documentation Blocks</link> section of the Doxygen manual: </para>