This is a question about how most Linux Systems use the ENABLE and ESTOP

For a LinuxCNC system running on a PC,  the screen is pretty well identical
to the MachineKit screen on a Beaglebone.  On the top left is the X button
for ESTOP and beside that the POWER (ENABLE)  button which clears the ESTOP
after the condition is cleared.

For the Xylotex HAL file and hardware the DB25-1 is an active low called
IOPWR#.  It's asserted low when the POWER button is clicked.  The suggestion
in the HAL file is that this signal be routed through the ESTOP NC contacts
along with any other NC circuit breaker relays and then into DB25-10 which
is the ESTOP input in the HAL file.

One of the MACH3 BoBs I have uses the DB25-1 pin as a 30A relay control and
is active high and this is supposed to provide power to the system.  So I
would imagine that BoB on a LinuxCNC system would have the POWER button be
active HIGH in the HAL file.  The user info for the BoB suggests running the
ESTOP connection through all the NC switches to ground.  A broken wire or
asserted ESTOP results in a high into the DB25-10 and signals an ESTOP.

I imagine, like MachineKit, LinuxCNC will then clear the ENABLE on DB25-1
and once the ESTOP condition is cleared clicking on the POWER (ENABLE)
button beside the ESTOP button will restart things.

Have I got it right?  The DB25-1 ENABLE signal is usually:
a) active high or 
b) active low 
on LinuxCNC systems?

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