The mystery of those Royal Copenhagen plates was too intriguing.  We kept searching. And we found a very logical interesting story.

Royal Copenhagen porcelain actually made plates specifically for different countries, during and after World War II, using the words like "weihnachten" on some plates, "noel" on others, "kerstmis" on others, and "vanoce" on others directed for sale in that country.  By 1952, their market was heavily influenced by the U.S. and the need to standardize their design was quite apparent.

They decided to remove all words except the date.  Thus, after 1952, they changed the design to include only the date in their design at the bottom of their Christmas plate design.

Mystery solved. See some of their other plates right here.
http://www.kannimports.com/danish_plates/all_danish_plates.html