pointerevents pressure

Hi, I may not know enough about this specification yet to make a justified
remark, but just in case I would like to mention something that I am
concerned about.

In the pointer events specification shown in the URL below, I noticed there
is the pressure attribute which is specified as being from 0 to 1.
However, 1 seems to be determined by the max possible value for that
device. I haven't coded using pressure before so can not say anything for
sure, but do devices have different max detection values, and if so, how
would it be possible to detect actual pressure?
If this is not physically viable across technology in the near future, then
it is not an issue, but it is one thing that got me wondering.

Thank you

http://www.w3.org/TR/pointerevents/