Mathematics 451: errata in the Internet age

``Geometry and Topology, Volume 7 (2003) Paper no. 23 has been withdrawn.''

I don't understand. What does it mean for a published journal article---
or a book, or any other document declared to be part of the permanent
research literature---to be ``withdrawn''?

Is the published paper still available from its supposedly permanent
home on the web? I glanced at the Geometry and Topology web page; the
answer seems to be ``no.'' If the 2003 Geometry and Topology papers had
already been printed and distributed to libraries, would the publishers
now be contacting the librarians, asking them to burn that volume?

I see a clear line between permanent documents and temporary documents.
A permanent document is a legitimate target of a bibliography entry; a
temporary document isn't. A temporary document might not be available to
the future reader. The only safe way to cite a temporary document is to
repeat what it says. Evidently, despite Geometry and Topology's claims
to be a legitimate journal, its papers are temporary. This bothers me.

---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago