Not all Dvorak layouts are created equal. Although the "letter key" layout is identical in every version I have seen, there are some differences in the positions of a few punctuation keys, and sometimes in the placement of command and control characters.
The official ANSI Dvorak keyboard (published in Cassingham's The Dvorak Keyboard) stack the left and right bracket characters ([]) on the same key, so you must press Shift to type a left bracket. A few keymaps that I have used follow this convention. These keymaps also handle brace characters ({}) the same way, although ANSI doesn't specify placement of brace keys.
Obviously, the ANSI solution is awkward if you type a lot of brackets and braces. Since computer folks type lots of brackets and braces, we shouldn't be surprised that many Dvorak computer keymaps ignore ANSI and place brackets and braces on facing keys (with the braces shifted). To allow this, the += key is usually moved down one row and placed between the slash keys.
In fact, the Dvorak layout with facing brackets appears to be the de-facto standard, ANSI Dvorak notwithstanding. I use the facing-bracket arrangement when I have a choice; because I like it, and because it is what I get when I don't have a choice. If you are a purist, don't knock existing Dvorak layouts because they don't adhere to ANSI; I have never seen a QWERTY computer keyboard that matches ANSI's QWERTY!
Another variation I have seen is in the handling of Ctrl and Command-key combinations. With most Dvorak layouts, each key's modified versions move wherever the base key moves.
At least one layout for the Macintosh leaves Ctrl and Command-key combinations in their original locations. I set up my first Mac keymap that way, but since I use several different computer types I caved in and learned how to touch type when I use the Ctrl and Command modifiers. I find it easier and less confusing overall.
Mac users might lament separation of the "big three" commands: Command-X, Command-C, and Command-V (Cut, Copy, and Paste). I did. But since then I've learned that using one hand for such combinations can cause repetitive-stress injuries. You are probably better off using your opposite hand to press the Command key anyway.
You might wonder how closely the modern Dvorak pattern matches Dr. Dvorak's first design. His patent only specified the letters and eight punctuation marks. While the pattern of letters has remained unchanged, every punctuation mark except the period has moved at least once. In Typewriting Behavior, Dr. Dvorak even published an optimized arrangement of the numerals (7531902468)!
Punctuation key changes have certainly been necessary over the years. Typists in 1940 doubtless had little call for the backslashes, vertical bars, and brace characters that many of us need today. On the other hand, when was the last time you saw (or wanted to use) a 1/2 or 1/4 key?
You can see several past variations of Dvorak and QWERTY keyboard layouts in Cassingham's The Dvorak Keyboard.
Variations in keymap arrangements deserve some thought, but don't forget how trivial they are in the big picture. QWERTY is a horrible keyboard layout, and any Dvorak layout you can get is an improvement!
Back to Introducing the Dvorak Keyboard.
Marcus Brooks -- 6 April 1996