Hello, everybody

i wonder question about how can be applied requirements management via Requirements module in TD.
It's known that there's model of 3 layer (or more layers)requirements: Busines,User and Functional requirements or another presentation - System,User, Software requiremets.
But my question is how to organize these differnt types of requirements in TD.
Whether each node which describes given feature should contain 3 subrequirements with corresponding names(Bussines,User,Functional),
or there should be 3 top requiremnts and all details should be in these 3, or other way.
If somebody has got any expirience in such organizing or any other ways please share it with me. I will very appreciate you.

Thanks in advance
and sorry for my bad english.