Question: I am working on a Windows Mobile application, and I am considering the use of directional buttons as an interface mechanism. Primarily, the enter (center) button. 

My question is whether I can rely on these to be present. The application will be for Windows Mobile 6.1 Professional devices, but I am designing it specifically to be usable with one hand only (i.e. trying to avoid the stylus at all costs). 

So is it a requirement for 6.1 Pro hardware to possess these buttons? Perhaps more to the point, is there an available specification where I can find out answers to these types of questions. 

Your contributions are appreciated.

Answer: 
Those buttons are definitely not guaranteed to be there. For examples of WM6.1 devices that DO NOT have directional pads, see several recent HTC devices:

* [Touch Pro 2](http://www.htc.com/us/product/touchpro2/overview.html)
* [Touch HD](http://www.htc.com/www/product/touchhd/overview.html)
* [Touch Diamond 2](http://www.htc.com/www/product/touchdiamond2/overview.html)
As far as I recall, the directional buttons (including center/enter button) are hardware-specific, meaning you can't rely on them being there for any device. Programming to these buttons on an HP iPaq (in Windows Mobile 5) required tapping into the HP API.

This may have changed for Windows Mobile 6+.