Old Archimedes Linker Option

I have an ancient version (V4.23H/DXT, copyright 1993) of the
Archimedes 8051 compiler. If I understand correctly, Keil created
it, and Archimedes Software sold it and provided support. The
manual for the compiler refers to the -a linker option for
controlling the overlaying of local variables, then goes on to say
that the option is "too new" to be included in the linker manual.

Sure enough, the linker manual (a separate book) doesn't mention
the -a option, but when I invoke the linker (V4.46H/DXT) with
nothing on the command line, it gives UNIX-like usage information
that includes this cryptic line:

    -a{iw(.)[.]{.}} Overlay control

Can anyone with a manual (or a really good memory!) explain how to
use this option?

Thanks,

-- Russ