in Europe, modulisation of the BIW tends to be based along the following lines (stick with this - its kind of difficult to explain in words - I have a powerpoint presentation that makes it a bit easier !!!)

The entire car can be thought of as a complex system made up of discreet sub-systems - which can be further broken down into other sub-systems eventually leading to components.  In days gone past - you might have referred to these as assemblies and sub-assemblies.  Each of these sub-systems is usually sourced with a full service supplier (generally a sub-contractor) who liases through the OEM system leader to ensure that the interaction between sub-systems/modules meets with their approval and packages in everyones best interests.

With respect to your specific question regarding the BIW

Module 1 refers to the main BIW as a complete assembly. It is made up of the following sub-systems

Module 1.1 - This is the front of the vehicle, and tends to capture everything made of metal attached to the BIW between the front bumper and the firewall.

Module 1.3 - this tends to be the middle to end of the vehicle between the firewall and the rear bumper.

Module 1.5 - this tends to be the bodysides and roof variants.

These are the most common sub modules - sometimes - depending on the vehicle manufacturer you are dealing with you can come across module 1.4.  If this is the case - it is usually the floor, which would normally be located in module 1.3.

Hope this helps - I haven't personally come acrossany web-sites which offer this type of adice - I got to know what I know from experience..........

best wishes

sean