Serhiy Storchaka added the comment:
https://support.pkware.com/display/PKZIP/Application+Note+Archives contains links to old versions of APPNOTE (the last is 6.3.3). But the actual version was at least 6.3.4 (I have a local copy).
All external links refer to http://www.pkware.com/documents/casestudies/APPNOTE.TXT. I think we should report a bug to PKWare.