Documentation for adb shell getevent / sendevent Is there any documentation on the format of the getevent and sendevent shell commands? specifically the ones for touchevents.
or is this device-dependent?

it is a bit hard to guess what those ids are doing.
There is some documentation on the AOSP site:


getevent


Plus several Howtos like e.g.


Android, writing events low level touch screen automated shell
Turning the output from getevent into something something that can be used
How to emulate key presses
adb shell sendevent, sending touch like events
Android, low level shell click on screen 


However, the answer to your question on Google Groups states:


  No, this is fairly device-dependent.  getevent prints a summary of all the devices so you know what those are.  The data generated for a device are generally the Linux kernel's event protocol, so you can look there for further help, but there is no guarantee that a particular device will be following those conventions.