Keling 5010 power supply wiring

[ronncat]

I am getting set to wire up my Keling 5010 Power Supply. The output side has a 5 pin connector. The first two are marked "+", the last two "-" and the one in the center with a broken oval. What does the oval mean? Do I need to hook that up to anything?
Thanks...

[ronncat]

Figured it out...Got brave and turned the controller on. Ran a voltmeter between the oval and the +/- leads. Read about 25V. This must be common. The broken oval must be a "C". Would be a neat way to pull 1/2 voltage from the transformer!