/added 10 Oct 2008
Postage due items from USA to Sweden

1 Jul 1971 to 30 Jun 1972
US foreign surface letter rate 15 c
Swedish foreign surface letter rate 85 öre
US handstamp shows amount to pay in US cents (normally double deficiency) and US surface letter rate.
In Sweden the indicated fraction multiplied by 85 rounded up to nearest 5 öre was normally paid by affixing stamps on the item.

Air mail card with 11 c. Correct rate 15 cent. Shortpaid 4 cent. US due handstamp indicates double deficiency 8 cent and foreign letter rate 15 cent. 8/15 of 85 öre = 45.33 rounded up to 50 öre have been charged in Sweden.