set its value with an assignment to `$$', and actions later in the rule
can refer to the value using `$N'. Since there is no symbol to name
the action, there is no way to declare a data type for the value in
-advance, so you must use the `$<...>' construct to specify a data type
+advance, so you must use the `$<...>N' construct to specify a data type
each time you refer to this value.
There is no way to set the value of the entire rule with a mid-rule