Liversidge, on 2020-May-08, 11:28, said:
With standard bidding, what is responder showing here?: 1♦-1♥-2♣-4♥
Responder shows:-
1. a heart suit that will play opposite a void.
2. enough general strength for 4♥ to have good chances opposite a minimum.
3. not enough strength for slam to be in the picture opposite a nondescript maximum.
It is a small window. Opener should generally pass unless they have an extremely suitable hand. Hrothgar's example hand here looks pretty good to me but perhaps with an extra heart.
Liversidge, on 2020-May-08, 11:28, said:
And here? 1♦-2♥-3♣-4♥
This one is solid hearts and about 16-17hcp (or playing strength to cause you to upgrade to that). Opener is invited to continue bidding with any suitable hand. Some pairs these days play it like miami as a picture bid showing specific features but I think that is still less common. A model hand for this might be KQJ AKQJxxx xx x.
In terms of bidding ladders:-
6-10-: 1♥ then 2♥
10+-12: 1♥ then 3♥
13-15: 1♥ then 2♠ 4SF
16+: 2♥