27th Aero Spad numerals : Black or Red?

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Does anyone have proof that the 27th Aero used black numerals with white boarder? Specifically, any fabric samples or actual first hand text describing them as black?

The reason why I ask is that there was a memorandum by Cheif of Air Service, AEF, June 16, 1918 ordering that serials should not use black but rather yellow or red as black was causing some confusion in combats with German national insignia.

So it would seem that they should in fact be red rather than black. Anything but black. Typically, 27th Spads have been drawn in black serials. I think it may very well be wrong. While were discussing the 27th can anyone confirm the blue/white ying yang on wheel covers? There are photos that have been retouched drawing in the ying yang but I do not see any evidence in same photos not retouched such as Luke's Spad.

[IMG]www.wingstrut.com/s13/s13_27thHarsma.jpg[/IMG]