Heathkit H-89 Accessory Card Cage

[wrljet]

What is the stub for that sticks up off the top of the accessory board card cage in the H-89?

 

[durgadas311]

I always thought it was to help support the cover, but I'm not sure that makes sense. It looks like you have the "FCC compliant" version, so maybe it makes contact with the carbon/conductive paint inside the cover?