Recent North American usage of the series boundary is divided: (1) following English tradition it is placed between the Toarcian and the Bajocian s.l. stages; (2) following central European tradition it is placed at the same position, but with the distinction of the Aalenian stage = Lower Bajocian s.l.; (3) following the resolution of the 1st Luxembourg Colloquium it is placed at the Aalenian/Bajocian s.str. boundary. Subsequent resolutions of the Cassis Meeting and, equivocally, of the 2nd Luxembourg Colloquium, however, rescinded the third usage because it conflicts with the original series definition and with the Lias/Dogger boundary; they also supported the Aalenian stage. Although no decision has as yet been taken by an internationally recognized body, the second alternative is strongly recommended in the meantime.