Re: prettify symbols question

["Alfred M. Szmidt" <ams@gnu.org>]

   > I'm slightly confused as how to add a new coding system, do I need to
   > first add a charset (the converted one would be an :ascii-compatible-p
   > t, and the native nil?)?

   Yes.  You will also need to prepare a mapping file, see below.  See
   the example of how we define, for example, coding-systems for
   MS-Windows codepages:

   (The mapping files are in etc/charsets; the :map attribute of the
   charset names the mapping file to use.)

Which are generated from the admin/charsets files, which in turn
sometimes pulled in from glibc.  So the easiest route is to add a
LISPM like charset mapping following glibc (and then also see if it
can be included there).  And then do,

(define-charset 'lispm
  "LISPM"
  :short-name "LISPM"
  :ascii-compatible-p nil
  :code-space [0 255]
  :map "LISPM")

(define-coding-system 'lispm
  "Lisp Machine encoding"
  :coding-type 'charset
  :mnemonic ?L
  :charset-list '(lispm))

So that sorts it out for the native one, but what should be done for
the Unix friendly mapping?  LISPM-ASCII, and similar as above?