2♦ opening is strictly Forcing and maybe any one of these 3 kinds of hand:

• A weak 2 in a Major
• A 19-20 HCP Balanced  (can include a 5 card suit in  a 5332 distribution)
• 5-5 or better either in Clubs & Hearts or Diamonds & Spades & a strict maximum 7LTC
  

Initially the responder makes  one of these 3 responses:

• 2♥: Default - heart support denied. This response is the preferred response wih FLAT weak hands with little honour strength [ Note: A 2H response does not necessarily imply any Spade support - but only makes it a little more probable...]
  
• 2♠: Promises good support for Hearts. Hx or xxx or better. [Note: this schema of 2Ma responses forces the Heart pre-empt to the 3-level when partner supports it. Also it does not necessarily deny Spades - but even if the Spade support is better than the Heart support 2♠ must be preferred to 2♥ to preferentially show the Heart support.
  
• 2N: Forcing. 15+ or 12+ with at least Hx card support for each major. If 2♦ opening is made in 3rd position,  2NT must be 15+  to allow for a probable weak major 2 bid, or even only a 5 card major.
• Rarer responses: These are available over most BETA opening bids - in many cases in any suit!
  
• 3mi: A Beta Break-out bid! 7+ card minor suit with limited values -likely to lack Major suits support. Theory is that playing in this minor provides value in terms of trumps  and is likely to  play better  than playing in any Major. If partner holds  a  strong  balanced hand, 19-20 and  the  minor suit is supported: then 3N  beckons.
  
• 4mi . Pre-emptive: Shows an 8+ card suit, no Major support, moderate values
  

Opener's rebid after a 2♥ response

Responders rebids:

• PASS Shows a weak 2 in Hearts
• 2♠ Shows a weak 2 in Spades
• 2NT Shows 19-20 Balanced FULL Puppet follows...
  
• 3♣|♦Opener's rebid after 2Ma or 2N response Show 5-5 or better ♣-♥ or ♦-♠ respectively, for continuations see  5-5+   bids [3N response & sequences]

Opener's rebid after a 2♠ response (promising heart support)

• PASS Shows a weak 2 in Spades
• 3♥  shows a weak 2 in Hearts
• 2NT Shows a Balanced 19-20HCP. FULL Puppet follows
  
• 3♣|♦Show 5-5 or better ♣-♥ or ♦-♠ Continuations see  5-5+   bids
  

If Opponents intervene

a) Before responder initial reply: With either a suit bid or a Double. Responder bids as follows:

• PASS if normal bid would be either 2♥ or 2♠ and holding <=9(10) HCP or the bid can no longer be made
• *|** If a forcing 2N was intended: (14)15+ HCP
• 3♦|♣ should be bid if still possible & 4♣|♦ has the same meaning over an opponents 3 other Ma intervention
• 2♥|♠ can still be made with their usual meaning  over an opponents  T-O double only if  holding (10)-(14)HCP

b) Intervention before opener's rebid:

• Opener can still call his  6|7 card major 2♠|3♥ i.e opponent simply doubled your partners 2♥ or 2♠  response or made a 3♦| natural minor suit o'call. He may also simply PASS!
  
• 3♣|♦  4♣|♦   can also be bid pre-emptively with  2-suited hands.
  
• *|** If a  balanced hand of 19-20 and 2N no longer available. Partner continues with FULL puppet as if 2N had been bid!: every bid still a transfer!  e.g.  2♦-2Ma-3mi(opp) *|** shows 19-20 balanced
  
•  3mi If a 2 suiter ♣-♥ or ♦-♠. If suitable even 4|5mi may be rebid competitively over opponent overcalls in either of the other two suits.
• Double for penalties.  (opponent committed a serious indiscretion!)
  

Opener's normal rebids following partner's 2NT response - as one would expect:

• 3♥ shows a weak 2 in Hearts
• 3♠ shows a weak 2 in Spades
• 3NT Shows a Balanced 19-20HCP. This bid is forcing at least  to the 4-level. Treat this like a 2N Baron bid - bid up the line.
  
• 3♣|♦Show 5-5 or better ♣-♥ or ♦-♠ Continuations see 3♣|♦ opening bids

Responders continuations

Following any Heart or Spade rebid (weak major 2)

• Opener is weak and usual continuation is PASS
• With appropriate values compete to 3 or 4 level
• Responder may have no support (singleton or void) but has a 6+card suit alternative and values in the suit. Bids his suit at the 3-level

Following a 2NT rebid showing a balanced 19-20

• Responses are full Puppet - everything is a transfer!
  
• PASS. Enough

Following 3mi rebid (2-suited hand)

Show preference: PASS or correct (to implied Major). Also may bid game in Major with a weak distributional hand.
Bid 3N distributional inquiry when able to explore Game or higher.