2 good points.. first of all..
...
yes, its only if you buy and then sell that SAME stock that same day.
and yes, it can get complicated, but lets say..
i bought some gtll at 3.. and the rest didnt fill.. it starts to run, so i buy more at 4 and flip all at 8 that same day.
AS LONG AS there was NO other stock buys or sells between those two, even though i changed my order at that, its still just one buy and so one sell... but if,, between my buy of 3 and 4, i sell or buy say, emll (pos) then it makes 2 diff buys.
that is the dumbest rule i have ever heard but i have been there and done that.. so, you are correct.