XForms Model

Hello,

What's exactly the XForm Model. Is the XForm Model specified by only the element <bind> ?
The new datatype are defined in the model too ?
Could you send me a example of a model ?

Thank you very much for your help

<signature>
  <name>Vaudan Rodrigue</name>
  <organisation>ESIS - HEV's Sierre</organisation>
  <email>rodrigue.vaudan@students.hevs.ch</email>
</signature>