:args named parcel argument in Grammar.parse

Author: cognominal

S05-regex.pod

@@ -4396,7 +4396,9 @@ All grammar objects are derived from C<Cursor>, so every grammar object's
 value embodies the current state of the current match.  This new grammar
 object is then passed as the invocant to the C<TOP> method (regex, token,
 or rule) of C<MyGrammar>. The default rule name to call can be overridden with
-the C<:rule> named argument of the C<parse> method.
+the C<:rule> named argument of the C<parse> method. This is useful for unit testing
+the rules of a grammar. As methods, rules can have arguments, so the C<:args> named
+argument is used to pass such arguments as a parcel if necessary.
 
 Grammar objects are considered immutable, so
 every match returns a different match state, and multiple match states may