On preflop, action starts with three options Raise 2BB, 3BB, 4BB, and when someone raises, action continues with, minimum raise, half pot raise, pot raise. on the flop action starts with a BB bet, and when someone bets, action continues with minimum raise, half pot raise, pot raise. Is this correct? Also of course one can raise any amount, but these are the options given by poker software.
I am not asking about the min-raise rule or reopening betting action. The question here is about the raise options given by the poker software as opposed to raising manually, and whether they have a formal definition or are they just arbitrary custom options. It's like 3-bet 5-bet continuation bet kind of thing.
On some other site i found there are different options:
initial preflop: min 3bb 5bb allin
initial bet: min 1/2 pot allin
reraise: min 2x 4x allin
sometimes: min 1/2 3/4 allin
So preflop an initial bet is expressed in terms of blinds, on other streets, an initial bet is expressed as pot size, a reraise is expressed as 2x 4x (two times more), and sometimes it is expressed as pot size 1/2 3/4.
My question is how are the betting button options given by poker software to the players determined?