-the Perl script `mkfiles.pl' from the file `Recipe'. If you need to
-change the makefiles as part of a patch, you should change Recipe
-and/or mkfiles.pl.
+the Perl script `mkfiles.pl' from the file `Recipe' and the various
+.R files. If you need to change the makefiles as part of a patch,
+you should change Recipe, *.R, and/or mkfiles.pl.
+
+The manual is provided in Windows Help format for the Windows build;
+in text format for anyone who needs it; and in HTML for the Mac OS X
+application and for the web site. It is generated from a Halibut
+source file (puzzles.but), which is the preferred form for
+modification. To generate the manual in other formats, rebuild it,
+or learn about Halibut, visit the Halibut website at
+<http://www.chiark.greenend.org.uk/~sgtatham/halibut/>.