1905 / 1920 Yacht Issues
Beginning in 1905, Germany began phasing in the use of watermarked paper on its new issues. Many color and perforation variations exist, primarily due to differences in peacetime and wartime printings.
These issues can be distinguished from previous Yacht Issues by the units of currency and the watermarks:
1901: Pesa/Rupien values, no watermark
1905: Heller values, no watermark
1905/1920: Heller/Rupien values, lozenge watermark
Numerous plate flaws exist.

MiNr. 37 Plate Flaw I — short lines in smoke (right)

MiNr. 39, A38, 39 Plate Flaw I — retouching in clouds above bow
In 1902, the Reichsdruckerei (Reich Printing Office) began printing in the margins of stamp sheets the internal order number under which the stamps were printed. This order number, or Hausauftragsnummer (HAN), varied in location, typically being found in the right or bottom margin.
For imperforate copies of several of thse issues, see here.
The larger format Yacht Issues of the German Colonies have slight differences in color, perforation, or frame/center types. For a detailed description of the frame/center types, see the guide to Colonial Frame & Center Types.
1905 / 1920 Yacht Issues
Beginning in 1905, Germany began phasing in the use of watermarked paper on its new issues. Many color and perforation variations exist, primarily due to differences in peacetime and wartime printings.
These issues can be distinguished from previous Yacht Issues by the units of currency and the watermarks:
1901: Pesa/Rupien values, no watermark
1905: Heller values, no watermark
1905/1920: Heller/Rupien values, lozenge watermark
Numerous plate flaws exist.

MiNr. 37 Plate Flaw I — short lines in smoke (right)

MiNr. 39, A38, 39 Plate Flaw I — retouching in clouds above bow
In 1902, the Reichsdruckerei (Reich Printing Office) began printing in the margins of stamp sheets the internal order number under which the stamps were printed. This order number, or Hausauftragsnummer (HAN), varied in location, typically being found in the right or bottom margin.
For imperforate copies of several of thse issues, see here.
The larger format Yacht Issues of the German Colonies have slight differences in color, perforation, or frame/center types. For a detailed description of the frame/center types, see the guide to Colonial Frame & Center Types.