Relevant ABF regulations:
Quote
Both members of a partnership must play the same system, including bidding and card play agreements.
Where, as a matter of style, members frequently adopt different approaches from each other, that difference
(or those differences) must be disclosed on the system card.
For example, we play 1S-2NT-3NT as a balanced hand showing 'extras' (and we have ways of showing 6 card suits or any shortness or any 5422 so this is basically 5-3-3-2). Opposite me, partner 'knows' that I have 17-19. Whereas for me I cater to partner having a 15+ NT style hand. Therefore a quantitative NT invite means different things.
Other sequences require more significant adjustments to cater to partner's style. For example, after 1S-1N, I probably want a 2C rebid to mean different things depending on the partner that opened 1S. If I'm at the helm it MUST show 4 because I don't need to do anything else with a 14 count, but partner does need to make a noise so 2C could be on a doubleton. This then effects how you might want to raise partner.
To what extent can bids after 1S-1N-2C-?? have different meanings depending on the partner that opened 1S?