_____________________________
|oooooo+O IDEHEADER...........
|oooooo-I 1stIdePIN...........
|
| 

Poor quick and dirty "diagram" show a part of pcb at a corner.
2*6 pads/holes symbolised with 'o' are card edge jtag contacts
+-OI are four header pins
+ - are LED positive and negative terminals
O = /OVR
I = /INT2