inconsistency in `File Usage'

[Alfred M. Szmidt]

`File Usage' states:

| Programs should be prepared to operate when `/usr' and `/etc' are
| read-only file systems.  Thus, if the program manages log files,
| lock files, backup files, score files, or any other files which are
| modified for internal purposes, these files should not be stored in
| `/usr' or `/etc'.

On GNU `/usr' is a symbolic link to `/', if one obeys the above
paragraph, then `/' must be prepared to operate as a read-only
file-system (which would include localstatedir and sharedstatedir,
which can never be read-only).  It would be much clearer to write that
exec_prefix, prefix, sysconfdir, and datarootdir should be prepared
for read-only file systems.