Yes, nationality identification in form of blue and yellow stripes. She would also have her name and Sweden painted on the hull. Nice of the yanks to give her name after a Swedish immigrant, John Ericsson, who amongst other things constructed the first effective marine propeller and the Monitor.
Thanks for sharing this gem of a photo--color views of her as KUNGSHOLM are extremely rare. This was taken at Panama during a cruise. When War broke out in 1939, SAL based her in New York for cruising, and she is indeed wearing her neutrality markings. Then when the US entered the War, she became the troopship JOHN ERICSSON.
See here for a broadside view of KUNGSHOLM's neutrality markings:
Yes, flat is flat in scandinavian too and holm is mostly used for small islands. I understand that the english language still has got a few scandinavian words and I guess you all got some good old viking blood in your veins?