The left and right most columns are shift keys which are duplicated (you can use with either hand). Refer to these as L1, L2, L 3, L4; R1, R2, R3, R4 OR as P1, P2, P3, P4; S1, S2, S3, S4 were P is the primary side on which the shift keys are pressed and held and S is the secondary side were the key is tapped to access a function. P may be either L or R and S is then the other. Combinations of the four keys access up to 15 alternate layers.
R2, R3 or R4 pressed and released without any other key being pressed generates ENTER.
P2 is "caps shift".
Px + S2 is shift lock for any layer. L1 or R1 releases the lock.
P2 + S4 is DEL
P2 + S3 is TAB
P2 + S2 is ESC
The arrow keys shift to PU, PD, HM, END; to media control (vol up and down and next and previous track).
The key to the right of L is the punctuation key which shifts to , : ; - ! ?
The bracket keys shift to the other bracket shapes: { [ < / " ' and their closing pairs. The keyboard maintains a stack so typing unshifted closing bracket matches the most recent opening bracket.
The four central keys in the bottom row all generate SPACE. These are individual keys so they can be flexibly assigned on non-alphabetic layers.