Cannot understand how Tax Rules work!!

Hi,

I have read a lot of documentation about that rules but I am not getting the idea :-(

Example:

If I have a rule that applies to:

- Regime: VAT France

- Content Owner: Global Configuration Owner

- Tax: FR Input Tax

and a Rule Type: 'Determine Place of Supply' is setup with a Default Value of: 'Bill To'

What does it mean for a 'Payables Invoice' Transaction for example? How is comparing the default value with the transaction to validate the rule and proceed with the validation of the other rules types?

Any help will be really appreciated.

Thanks,

cv