setting machine zero

Hi,

I am trying to configure sherline and flashcut to something that can
simulate their bigger brothers (learning purpose, trying to program
like for big machines). I understand most cnc router have their
machine zero at the maximum +X +Y and +Z (max. right, max. forward,
max. top)

So with flashcut 2.0, In the machine configuration, I set max x-axis
lenght to 9, max. y to 5 and max z to 6. Starting from program zero,
I point move to X=+9, Y=+5, Z=+6. At this point, I zero the machine
coordinates. The software draws a blue box showing the limits for z
at -6, which will be just like their big brothers, the the blue box
for xy plane extend from (9,5) to (18,10) which means that if I
attempt to move to say x=1, this will be an illegal move as it will
be out of the machine envelope.

Is it that for flashcut, the only way to set machine zero is to set
it at min. x (extreme left), min. y (nearest operator), max z?

Any insight highly appreciated.

Thanks

Andrew