Along with the .sch file you can find all the relevant points on the board. The .brd file includes all components, names, even those that are not printed on the shield. I summarized all major components and platinum points in the following image.
In general I can say: There are enough ways available to connect the board to whatever. It is well recognized that many inputs and outputs are not used, but only because to make the board stackable. For those who use the board as a shield , it's really plug 'n play. But those who wants "outsource" the shield -like me- it would be necessary to deal with the pinout.
On the photo it looks like you have four solder points to connect ground (Gnd). Really four? Let's have a look at the layout. Wow! Only one single platinum point is possible to use. That's exactly what I said yesterday: A look at the layout is worth it!
Short explanation to the yellow boxes:
Q1 = level converter SDA
Q2 = level converter SCL
Q3 = level converter SCK
Q4 = level converter RSTP
FSR = Voltage regulator 5V/3.3V
IRQ = Connected to an LED, showing the status of the interrupt (IRQ)
The green lines represent the two lines SDA and SCL They can be picked up at five different points:
SDA: Top left 2x (SDA), MOSI (separate power strip), and the bottom right 2x (Analog In 4)
SCL: Top right 2x (SCL), SS (SPI socket) and the bottom right 2x (Analog In 5)
The yellow lines are the points that I will connect to a 5-pin male header.
Next, it the blog goes on with the " Wiring" and the first test run.