My primary input languages are Chinese (Pinyin), English, and Japanese (Romaji). Therefore, this layout is optimized specifically for this linguistic combination. It is also designed to be quite programmer-friendly, though I am still finalizing the optimization for coding symbols.
Design Philosophy:
While the initial idea stems from Maltron and Dvorak, the end result differs significantly from both. Here are the key features:
Finger Movement: Aside from the index fingers, I have completely eliminated downward movements for the other three fingers on the home row.
Pinky Movement: Instead of moving down, the pinky moves outward (similar to the Enthium layout). The letters assigned here are Q, X and J, V.
No Rolls on Weak Fingers: Contrary to the philosophy of Workman or Colemak, I have strictly avoided rolling on weak fingers.
Double Letters: Almost all double letters (across all languages I know, including those heavy on double letters like Finnish) are assigned to strong fingers or the top row of the middle/ring fingers for easy consecutive strikes.
Because two letters are bound to the thumbs, the main key area now has extra capacity. This allows you to freely place any symbols you like on the bottom row of the middle, ring, and pinky fingers on both hands.
There is still room for language-specific optimization (e.g., swapping G/R or J/V left and right; Z is on the index finger mainly for Chinese usage). However, after 100 hours of testing, I haven't encountered any words that are truly difficult to type. It feels very ergonomic for long sessions.
If you need to adapt the layout for a specific language, you can first make small adjustments in the following ways, as they will not fundamentally affect the results:
swap the top row and home row positions for the same finger (except the index and little fingers);
freely permute the positions assigned to the index finger, except for its starting position;
swap the top‑row positions of the ring finger and middle finger.
If you don’t need to type Chinese, you can assign the digits from the low layer to the top rows of both hands and to the bottom‑row positions of the index fingers, and place commonly used punctuation on the home row. 43(09)215876 digit order I currently use on the low layer is actually a compromise for specific languages. In fact, if you look at digit frequencies in general (i.e., outside any particular language context), the order is 0 1 2 3 4 5 8 6 9 7. Mapped across both hands, an arrangement like 9 7 1 3 5 on one side and 4 2 0 6 8 on the other would be much better than my current scheme.
The fact that the pinky does not move vertically means you can freely choose either Q or X (left hand), and either V or J (right hand), as the starting position, much like placing your fingers on a piano.
If you need to modify the layout for a specific language, it is advisable to avoid pinky double‑taps, repeated horizontal movements, or patterns that tie the pinky too closely to the ring finger. For example, in English, sequences like xco or hjk(hdv) although not very frequent, can still feel uncomfortable
I’ve named this layout “APU” after our three‑month‑old kitten. If it weren’t for her, I probably would never have thought of using the thumbs for typing.
