What is SpaceFN and why you should give it a try
The SpaceFN concept - setting up your space key as a layer switch when held - is probably one of the most useful tweaks in the keyboard hobby. Let me explain how it works. My SpaceFN article on kbd.news made some rounds recently - quite surprisingly given the age of this concept. This piece you're reading is a condensed version of the full post. If you're left with unanswered questions, you'll most likely find the info you're looking for in the original write-up. On my imaginary top list of the most useful keyboard features, tweaks and hacks, SpaceFN would deserve a podium finish for sure. But what makes it so special? In short: SpaceFN is easy to implement, easy to learn, costs nothing, can be used with any keyboard, and can improve your productivity instantly. I will list its benefits below, but can state right at this point that the SpaceFN concept, setting up your space key as a layer switch when held, is clearly one of the most useful tweaks in the keyboard hobby....
Apr 30, 2024
https://geekhack.org/index.php?topic=77576.0
However I believe that is the exception to the rule. Most commonly we see "R1" at the top (function row) and "R4" at the bottom (spacebar row). As one quick example, from the Nautilus drop:
So I think the safest assumption here would be to go with the common naming scheme and get one R2 and three R3, as Mudkipslaps mentioned.
Interesting side note, I was looking at my Realforce 87UB and noticed that the up arrow keycap is shaped the same as the caps in the Enter key row, even though it resides a row below in the Shift key row. So much minute attention to detail in Realforce boards.