You've found yourself here because you scanned the code in the R4 Protocol Book.

That's the right move if you'd like to go deeper. The book contains everything you need to implement the system, but sometimes implementation can be the hard part.

The next page has something to help with that. It's not free - it's £7 - but it's worth a lot more than that.

If you want the details, put your name and email below.

Your email won't be spammed. You'll hear from me a handful of times throughout the year.