How GUID is Caculated?

Hi,

Can any one please help me.

We have 8 line items in one Quatation, this quatation is availbale in one Opportunity.

I wolud like to know how system generate GUID Values for these 8 line items.

I need this in order to understand one ABAP Programme. In this programme these 8 GUIDs are sorted and only highest GUID is considered for further calculation.

So, how system generates these GUID values. Based on what factors? for which item it will give highest value GUID.

Hope i am clear..

Thanks

Tony