As far as I can tell mos_getkey responds to shift on its own. So if you do 1 + for example you get $31 $00 $2B as a sequence. I'm not quite sure if this is a bug or a documentation fault. If the latter such behaviour is somewhat unusual and should perhaps be mentioned in the documentation.
(Workround : filter out key code $00)
As far as I can tell mos_getkey responds to shift on its own. So if you do 1 + for example you get $31 $00 $2B as a sequence. I'm not quite sure if this is a bug or a documentation fault. If the latter such behaviour is somewhat unusual and should perhaps be mentioned in the documentation.
(Workround : filter out key code $00)