Supplier tax invoice exchange rate in AP

Hi All,

Please help me with my question . There is a field on AP invoice header Supplier tax invoice exchange rate I have few questions :

1) What is the use of this?

2) Is this just free text field or any validation is used?

3) Is this dependant on any supplier setup?

4) is this related to system transaction exchange rate?

5) is this related to supplier tax invoice?

Many Many Thanks

in advance kindly reply

Thanks