BART is employed after 1♠ -p - 1NT- p - 2♣ (where 1NT is forcing or semi-forcing). In BART 2♦ is artificial and asks partner to bid 2♥ unless partner has a hand that would bid over a 2♥ signoff.  BART sacrifices the ability to bid 2♦ weak, but allows a partnership to distinguish, between, a weak and strong 2♠ preference, a weak hand with just hearts or a hand with hearts that also has other places to play, and it also allows responder to show 4 card club support with out going past 2NT.

The original version of BART switched the meanings of 2♦ and 2♥, but this version allows you to show more hand types and is just as easy if not easier to remember.

1♠ -1NT-2♣

• 2♦             BART - either to play 2♥, or various other hands.
• 2♥             5 hearts and another place to play (such as a doubleton spade, 4 clubs, 5 diamonds, 1543, etc.)
• 2♠             Either very weak with 3⁺ spades or up to 8 HCP with doubleton spade.
• 2NT           10⁺ - 12 (with 10 HCP and 2 spades, you can also bid 2♦; 10 HCP and a stiff spade may need to bid 2NT). Should deny 4♣s.
• 3♣             Courtesy raise with 5⁺♣s.
• 3♦             FJS for clubs. NOT FORCING but highly encouraging. 4♣ not forcing. Other non-game bids forcing, including 4♦.
• 3♥             FJS for clubs, as above.
• 3♠             3-card limit raise.

1♠ -1NT-2♣ -2♦

• 2♥             All minimum hands. Opener only breaks with a hand good enough to bid over a natural ♥ signoff.
• 2♠             Artificial, shows minimum strength up to about bad 16 but would raise a natural 2♥ signoff, eg. Axxxx QJx x AKxx.
• 2N              Extras, 5224 or 5134.
• 3♣             Extras, 5-5.
• 3♦             Extras, 5044.
• 3♥             Extras, 5314.
• 3♠             Extras, 6-4.

1♠ -1NT-2♣ -2♥

• 2♠              Usually stiff or void in hearts though can be small doubleton. Nonforcing ask for the other place to play.
• 3♥             Invitational raise with 3 card support likely (but maybe KQ xx in red suits) .
• Others         Same as over 2♦.

1♠ -1NT-2♣ -2♦ -2♥

• Pass            You play this, even with short hearts.
• 2♠              Normal preference but on the good end, about good 8 to bad 10.
• 2N              10 to bad 12, natural invite but promises exactly 4 clubs. If opener pulls to 3♣ that is to play, other bids are forcing.
• 3♣             Invitational raise, 5+♣ s.
• 3♦             Weak with diamonds, to play here.
• 3♥             2-6 in the majors, invitational (1♠ - 3♥ is ostensibly 1-6 in the majors if you play downward invitational jump shifts).
• 3♠             Balanced limit raise, will pass if you bid 3NT.

Now, it may seem like quite a lot to digest all at once. The easy way to remember the difference between bidding something directly and going through 2♦ is that going through always shows something extra. For example after 1N-2♣-2♦-2♥: 2♠ is stronger than bidding directly, 2N shows 4 clubs, and 3♣ also has more values then bidding directly.

If you do choose to play BART, your partnership should bid 2♣ on a doubleton instead of a 3 Card ♦ suit.  This allows you to take fuller advantage of your gadget and responder also knows that opener’s 2♦ bid promises 4.