This is a piece of painted German aircraft fabric measuring 21" x 18"  from the right side of a Pfalz D.XII rudder.  In the upper left corner is the transfer or decal of the Pfalz Flugzeugwerke. The photograph below it is the reverse side against which can be seen rust stains about 12" apart and that is the approximate spacing between the top and middle tube of the three horizontal metal tubes or ribs of the Pfalz D.XII rudder. There are threads coming through the back where the fabric would have been tied onto the tubes; on the front they are covered by strips of horizontal fabric.

Written in pencil on the reverse are the numbers "912," or so I thought.  For many years I described what I saw as "912" and thought that these numbers were the last three digits of the four-digit work number or aircraft serial number, in which case this fabric would be from Pfalz D.XII 2912/18.  Then in 2006 I acquired another piece of rudder fabric with similar paint, an identical cross and the same rib tape spacing - as well as penciled marking on the reverse side which was easier to read and appeared to be "D12" with the "D" being in old German script.  It's then I realized that both pieces, not just the second one, were marked similarly as "D12."  This was most likely done by the factory worker  responsible for making rudder coverings identifying which aircraft type each rudder covering was meant for, such as a D.III or D.12. 

The thread count is 50 yarns to the inch in either direction. This is readily seen in the bottom right photograph which is an extreme close-up of the fabric alongside a ruler as seen through a photographer’s loop and back-lit with a photographer’s light-box. The Pfalz werks decal is shown in the bottom left photograph and is one of at least two known to exist. The commonly accepted yet flawed version of the Pfalz decal is a reproduction apparently done by someone looking at a very small and damaged 35mm decal attached to Pfalz D.XII No. 2600/18 in Canberra before that aircraft was restored. It depicts a river and the town where Pfalz had its factory. In actuality, the Pfalz werks decal represents an inverted bird-of-prey over a stream with a cliff to the left. Credit is due to Dan-San Abbott who carefully compared the flawed Canberra reproduction to this decal and identified how the reproducer mistook the cliff and bird-of-prey for town buildings and a church spire. The photo in the middle below is from a Pfalz werks advertising poster care of Aaron Weaver.