i thought this may have been a difference in your version of rc and the one i was using. now i don't think so.
; 9fs sources
; exec /n/sources/plan9/386/bin/rc
; a=(1 '2 3' 4 5)
; s a
; whatis a
a=('2 3' 4 5)
; s a
; whatis a
a=(4 5)
; s a
; whatis a
a=5
; s a
; whatis a
a: not found
- erik
