IFS=
set "abc" "def ghi" "jkl"

set ${1+$*}
printf '<%s>\n' "$#" "$@"

set "abc" "def ghi" "jkl"
set $*
printf '<%s>\n' "$#" "$@"

printf '<%s>\n' $* ;
printf '<%s>\n' ${q:-$*} 
printf '<%s>\n' "${q:-$*}"

IFS=:
printf '<%s>\n' $* ;
printf '<%s>\n' ${q:-$*} 
printf '<%s>\n' "${q:-$*}"

unset -v IFS
printf '<%s>\n' $* $@