In some documents, internal hyperlinks include the original name of the HTML document as well as the fragment. Because the document is now named "index.html", these links are broken. Eg, In "XSL Transformations (XSLT) Version 1.0" (REC-xslt-19991116), all hyperlinks in the table of contents are broken (eg "Introduction"), as are all subsequent internal hyperlinks (eg "XML" in the first paragraph of the introduction). I can't tell if this is a problem in the upstream document or not. It certainly makes the document almost impossible to use. However, not all of the documents in the package have this problem.
Dear submitter, as the package w3-recs has just been removed from the Debian archive unstable we hereby close the associated bug reports. We are sorry that we couldn't deal with your issue properly. For details on the removal, please see https://bugs.debian.org/1013274 The version of this package that was in Debian prior to this removal can still be found using http://snapshot.debian.org/. Please note that the changes have been done on the master archive and will not propagate to any mirrors until the next dinstall run at the earliest. This message was generated automatically; if you believe that there is a problem with it please contact the archive administrators by mailing ftpmaster@ftp-master.debian.org. Debian distribution maintenance software pp. Thorsten Alteholz (the ftpmaster behind the curtain)