Hi
Betfair will match bets at the best available price.
if the current best lay price is 1.96 and you put in a lay bet at a price of 2.00, it will be immediately matched at 1.96
however you can put in a back bet, which will be unmatched and waiting on the lay side of the book at price 2.00
trigger:
back, price: 2.00
condition: selections lay price is between r_ticks(2, -4) and r_ticks(2, -1)
or another way to write that is:
back, price: 2.00
condition: selections lay price is between 1.96 and 1.99
now if best price is above 2.00, e.g. 2.08, then you can put in an unmatched lay bet at 2.00 which will be waiting on the back side of the book:
lay, price: 2.00
condition: selections lay price is between 2.02 and 2.08
hope that makes sense