Questions about Submodels

Hi IBIS folks. I'm working on our procedures for creating IBIS models of devices
with Bus Hold, and struggling through this section 6a on Submodels. Help.

First of all, are submodels a section that is entirely contained within a model
section, or are they independant and inheritable by other models? For example,
if I have an input model:

|******************************************************************************
[Model] LVTH244_DATAIN_33
Model_type Input
Vinl = 0.8V
Vinh = 2.0V
C_comp 3.35pF NA NA
|
[Add Submodel]
BUS_HOLD_33 Non-Driving
|
|******************************************************************************

Does the submodel BUS_HOLD_33 have to follow the data in the LVTH244_DATAIN_33
model and be within that model, or can all of the submodels be at the end of a
file in a separate section following the models?

Further, once I have declared a "[Submodel] BUS_HOLD_33" submodel within the
LVTH244_DATA_IN_33 model, do I have to include the complete submodel again
within the LVTH244_OE_IN_33 model, or can I just simply call it and expect the
simulator to use it. If submodels do in fact turn out to be local instead of
global and inheritable, is there any namespace conflict?

Next is the question of data extraction for bus-hold. The clamp curves in the
main model contain all of the data on the VI characteristics of the bus
hold-circuitry. See the attached pdf file for an example. What is the purpose of
the trigger and pullup/down data in the submodel section? What information does
it provide that is not already available in the clamp curves of the main model?
How do you extract the Ramp data (test setup).

Finally, in the spec there is the following sentence:
> | The [Pullup] and [Pulldown] tables both are used to define an internal
> | buffer that is triggered switch to its opposite state.
What does this mean and is this sentence grammatically correct? I can't figure
it out.

Thanks.

-- 
Regards,
Stephen M. Nolan