I've just published draft #4 of SRFI 140.  It was submitted
by Per Bothner, author of the SRFI.

  <http://srfi.schemers.org/srfi-140/>

The diffs can be found here:

  <https://github.com/scheme-requests-for-implementation/srfi-140/commits/master>

Here are Per's notes on this change:

  I think I added all the missing pieces for the SRFI-140
  (Immutable strings) specification, including specification
  of libraries to be provided. It should now be more-or-less
  independent of SRFI-135.

  There is still work needed on the preamble, including the
  abstract, which is written in reference to SRFI-135.

  The implementation is still unfinished. The "invoke"
  branch of Kawa's git repository has the necessary
  skeleton, but many of the procedure are missing.  There is
  no reference implementation; that will probably be written
  as a wrapper around SRFI-135.

Regards,

SRFI Editor