Device Detection segment "smartphone"


Thank you in advance to the community for any input you can provide, we are new to Piwik and are trying to learn the ropes.

Can anyone shed any light on what the definition/secret sauce is which Piwik uses to calulate DeviceDectection Segment for “Smartphone” and part two is that definition editable?

But really just the definition of “Smartphone” would be helpful.

thank you.