references within @copying

[Eric Blake]

In the M4 manual, I was experimenting with an attempt to put a hyperlink to the 
FDL from the copyright page:

@copying

This manual is for @acronym{GNU} M4 (version @value{VERSION}, @value{UPDATED}),
a package containing an implementation of the m4 macro language.

Copyright @copyright{} 1989, 1990, 1991, 1992, 1993, 1994, 2004, 2005,
2006, 2007 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the @acronym{GNU} Free Documentation License,
Version 1.2 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts, and no
Back-Cover Texts.  A copy of the license is included in the section
entitled @ref{GNU Free Documentation License}.
@end quotation
@end copying
...
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top
@top GNU M4
@insertcopying
@end ifnottex
...
@include fdl.texi

This worked great for the pdf version.  However, for the info and html 
versions, it complains:

../../doc/m4.texinfo:79: Next field of node `Top' not pointed to (perhaps 
incorrect sectioning?).
../../doc/m4.texinfo:288: This node (Preliminaries) has the bad Prev.
makeinfo: Removing output file `/home/eblake/m4/build/doc/m4.htp/index.html' 
due to errors; use --force to preserve.


Reverting this change makes the error go away:

@@ -51,7 +51,7 @@ under the terms of the @acronym{GNU} Fre
 Version 1.2 or any later version published by the Free Software
 Foundation; with no Invariant Sections, no Front-Cover Texts, and no
 Back-Cover Texts.  A copy of the license is included in the section
-entitled address@hidden Free Documentation License.''
+entitled @ref{GNU Free Documentation License}.
 @end quotation
 @end copying
 
which means there is something about the use of @ref within @copying that 
messes up makeinfo.  Is this worth fixing, so that the copyright page can have 
a hyperlink to the FDL rather than just a textual reference?  Also, if this is 
fixed, is this approach worth documenting in maintain.texi and in the 'GNU 
Sample Text' appendix of the texinfo manual as a suggested way to use the FDL 
in an FSF manual?

-- 
Eric Blake