/added 15 Aug 2005
Postage due items from USA to Sweden
ca April 1888 to 31 Dec 1891
US foreign surface letter rate 5 c
US Conversion rate 1 US cent = 5 goldcentimes
Swedish conversion rate 1 goldcentime = 0.80 öre for letters, 1 goldcentime=1 öre for postcards and printed matters
US marking shows the amount missing in goldcentimes.
In Sweden the indicated amount was doubled and multiplied by 0.80 for letters and 1 for postcards and printed matters. The amount due was paid by affixing postage due stamps.

 
Letter with 2 cent. Correct rate 5 cent. Shortpaid 3 cent. US due marking indicate missing amount 3x5=15 centimes. In Sweden the amount have been doubled and multiplied by 0.8 and 24 has been indicated in blue manuscript. Of some reason no postage due stamps have been affixed.