In addition to the large and small Papua inscription, if you are using the Stanley Gibbons catalogue, you will also need to determine the difference between a horizontal and vertical rosette watermark. It took me a long time to figure out that the size of the rosette determines whether it is horizontal or vertical. Measure the rosette and the wider version is what counts. So a horizontal rosette will have the widest portion running horizontally.
In the image below the rosette would be considered vertical.
