-The only option it accepts is "-c" to operate on a specific tax class
-(named after the -c). If this isn't included it will operate on records
-with null tax class.
+Options:
+
+-c <taxclass>: operate only on records with the named tax class. If not
+specified, this operates on records with null tax class.
+
+-t <taxname>: operate only on records with that tax name. If not specified,
+it operates on records where the tax name is either null or 'Tax'.