In Jack's session there was some discussion about the auction 1D-2D-2M. Does it promise exras? Does it show long diamonds? Here is what Bridge World Standard says:
"Opener's reverse of the form one diamond — two clubs — two of a major does not promise extra values and is ambiguous as to diamond length."
Thus 1D-2C-2H could be on a 12 count and four diamonds, or even three diamonds if opener is 4=4=3=2. Opener can be 4=4=4=1 and a 12 count.
I am pretty sure that the bots play 1D-2C-2M as showing extras [Yes, they do, I checked, see below] but I will check that out and get back on that.
Sticking with BWS for the moment, after 1H-2m the following applies:
"After a two-over-one response [to a major suit opening] , a two-level reverse or a non-jump three-level new-suit bid shows extra strength, but two notrump or a single raise may be based on a minimum hand."
This is how I have played for a long time.
The logic:
After 1H-2m, opener, with 4=5 in the majors, can bid 2H (this does not show 6) and wait for responder to show spades if he has them
After the 1H major we can wait to see about spades.
However, after 1D-2C now we have to explore both for a spade fit and a heart fit and, to me, it seems best to get started by having opener rebid 2M if he has four cards in a major.
I am not claiming this is perfect, nor am I claiming that this is what everyone does, but it's workable and it is what BWS does.
Added: I checked the bots. After 1D-2C, they play that 2S shows 16-22 total points (hcps plus any distribution). It does not promise any extra length in diamonds.
Quick summary:
1H-2m-2S sows extras with the bots and in BWS
1D-2C-2M shows exras with the bots, but not with BWS. And does not shoe extra diamond length in BWS or with the bots.
I might look around a bit at other sources.