``imports'' clause

> The problem here is some confusion between LCL functions 
> and LSL operators. In the ensures clause, only LSL 
> operators may be used.

Well, there was any confusion in the use of LCL functions in
the ensures clause. I purposely used them since I believed 
it was possible (as it is suggested in the literature).

So, this means that LCL operators cannot be used in
other LCL modules? 

I think that the ``imports'' clause has been introduced 
in order to allow a ``structured'' modularity. If inclusion
between LCL modules is not possible, then the LCL layer
specification is reduced to a flat set of independent 
modules. Is there a reason for this?

I will really appreciate any opinion about this.