AP- Why exchange rate type between Post invoice and Post payment is different ?
I have question
when post AP invoice , document type KR
document date = 11.12.2009
posting date = 31.12.2009
entry date = 05.01.2010
this document using exchange rate type B (standard translation at bank selling rate) on 31.12.2009 (use posting date )
but when post payment for above document,document type ZP
document date = 25.06.2010
posting date = 25.06.2010
entry date = 24.06.2010
this document using exchange rate type M (standard translation at average rate) on 23.06.2010
why do post invoice and post payment use different exchange rate type?
and why at payment donot use posting date for get exchange rate ?