Rafi Rubin wrote:

quoted

Single touch should be goverened by one of BTN_TOUCH or ABS_PRESSURE.
BTN_TOOL_DOUBLETAP is a two-finger event.

That definitely makes sense to me.  I really don't know why wacom uses
double tap there.

Is there any harm in letting through the BTN_0 events?  Is the "rdesc"
mapping defined by the hardware or hid?

I cannot imagine BTN_0 will do any harm. In synaptics, the BTN_X buttons are
mapped to multibuttons without clear-cut usage. The button events that carry
well-defined semantic meaning with regard to touch screens are BTN_TOUCH (any
finger), BTN_TOOL_FINGER (one finger), BTN_TOOL_PEN (pen), BTN_TOOL_DOUBLETAP
(two fingers) and BTN_TOOL_TRIPLETAP (three fingers or more).

Henrik