In looking at the General Convention Chart of the ACBL, it seems the standard 6-card weak 2♦ isn't permitted. Since I know that it is how almost every ACBL-player plays 2♦, I must be misreading the chart. But I don't see how. . .
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b) a three-suiter with a minimum of 10 HCP.
4. STRENGTH SHOWING OPENING AT THE TWO LEVEL OR HIGHER that
asks for aces, kings, queens, singletons, voids or trump quality and responses
thereto.
5. TWO DIAMOND ARTIFICIAL OPENING BID indicating one of:
a) a strong hand.
b) a three-suiter with a minimum of 10 HCP.
6. OPENING BID AT THE TWO LEVEL OR HIGHER indicating two known
suits, a minimum of 10 HCP and at least 54 distribution in the suits.
7. OPENING TWO HEART OR TWO SPADE BID showing a weak two bid, with
a four-card or longer minor.
http://web2.acbl.org...ntion-Chart.pdf