I'm referencing this page: Proto Shield Rev3 (Uno Size) — Arduino Official Store
A couple corrections for the above description, both in the "SPI connection section". (Feel free to remove this comment when the corrections are made).
- "The ICSP connector available on the shield hove his connections made directly to the SPI pins." should probably read more like "The ICSP connector available on the shield has these connections made directly to the SPI pins.", and of the three boards I looked at the schematics for (UNO, Leonardo, and Mega2560), only on the UNO are D11-D13 normally SPI pins. (See my comments below.)
- According to the schematic, pin 5 of the ICSP connector is connected to /Reset, not to D10.
Also, why have these connections hardwired instead of longer pins on the downward facing housing to make it a pass-through? The connections are redundant on the UNOr3, and on two other boards that I looked at the schematics for (Leonardo and Mega2560) these connections basically make 3 GPIO pins unusable for other things because D11-D13 are not normally connected to dedicated SPI pins on those boards.