On Fri, Jul 28, 2017 at 8:18 AM, William D Clinger <xxxxxx@ccs.neu.edu> wrote:

The UTF-32 encoding does have another advantage over vectors
of characters:  On 64-bit systems, R7RS vectors of characters
occupy twice as much space as bytevectors with UTF-32.

Of course.  For some reason I was thinking in a 32-bit (mental) box at the time.
This wouldn't matter very much if procedures resembling R6RS
bytevector-u32-native-ref and bytevector-u32-native-set! were
available in R7RS Red Edition,

The Orange Edition, which is concerned primarily with numbers, will have (subject to vote, of course) SRFI-4 numeric vectors.   See <https://trac.sacrideo.us/wg/wiki/OrangeDocket>.