What does this red dot mean on the "Flatline " build seen here?

[rosssurf]

What does the red dot on the LED/LDR mean?The small one in the upper right of the VTL5c3. I know about the trace cuts underneath I am doing this buildhttp://aronnelson.com/gallery/bcreekmur/flatline_compressor

[The Tone God]

Its the anode of the LED in the optocoupler.

Andrew

[rosssurf]

Thanks Tone God