There were previously no Dvorak specific underscore and plus key codes. For a keyboard like the Planck which has layers directly to shifted versions of special character keys you were unable to produce those characters using the Lower layer.
By testing I found out that, at least on Linux using the Swedish layout,
two macros present on this file were wrong, for the backslash and pipe
keys. Jack helped me find the correct combination for the backslash and
that led me to the right one for pipe.
Didier Loiseau