checkword () { check "$1" "$R_WORD" "$2"; }
checklabel () { check "$1 label" "$R_LABEL" "$2"; }
+## Boolean canonification.
+boolify () {
+ var=$1 what=$2
+
+ eval v=\$$var
+ case $v in
+ 1 | y | yes | on | t | true) v=t ;;
+ 0 | n | no | off | f | false | nil) v=nil ;;
+ *) echo >&2 "$quis: bad boolean $what \`$v'"; exit 1 ;;
+ esac
+ eval $var=\$v
+}
+
###--------------------------------------------------------------------------
### Key storage and properties.