rdf file and blackberry touch screen devices

from rdf file http://www.blackberry.net/go/mobile/profiles/开发者_如何学编程uaprof/9530/4.7.0.rdf

how do we know that device is a touch screen device?

You could try to infer it from this line:

 <prf:Keyboard>Virtual</prf:Keyboard>

But that would break down for devices such as the Torch which have both a touchscreen and physical keyboard (it's RDF has "Qwerty" for the Keyboard value).

The safest way to know is by using Java APIs, such as Touchscreen.isSupported()