Morgans wrote:
saction

amount known yet just to make sure there will be enough funds available.
Examples are pay-at-the-gas-pump transactions (usually $50 is

preauthorized

before you start pumping),

Actually, that's WRONG. What they usually do is put through a $1
preauthorization. The $50 limit they put on the pumping is a number
that the point of sale determines is the max they will do based on that
$1 preauth.