[R-sig-ME] interaction term in null hypothesis

[Junqian Gordon Xu]

I have a quick question for a simple model as below:

> Fix + (1 | Rand) + (1 | Rand : Fix)

Which one is the null hypothesis:

> 1 + (1 | Rand)

or

> 1 + (1 | Rand) + (1 | Rand : Fix)

To me the interaction term (1 | Rand : Fix) does not make much sense if
no fixed effect term is present in the model, but I'm not sure.

Regards
Gordon