AOpen AP43 User Manual page 24

Hardware Setup
Set a jumper switch as follows:

To close a jumper, insert the plastic jumper cap over two pins of
a jumper.

To open a jumper, remove the jumper cap.
The following conventions are used to represent the proper jumper
settings:
When you open a jumper, attach the
plastic jumper cap to one of the pins so
you won't lose it.
2-6
Open
Closed (2-3 position)
User's Guide