decal's blank

Occasionally I have found blank decals like that.  They were intended to go under, or over, printed decals of the same shape, to change the color.  For instance, I had white circles for a WWII Avenger that were intended to go over the red meatballs in the center of the US Star & Bar insignia, to simulate the red being painted out for extra camoflage on a certain historic mission.  The result was a very faded, slightly pinkish meatball.  The effect was pretty good, it looked like it had been intentionally obliterated, but not quite.

the white outlines are underlaying decals intended to make a certain decal "pop" , and in many cases allow a better print job without ink muddying that was common with MicroScale decals in the 80s.  Lets say you have markings for AiraCutie, you may have a full size white decal that will be laid first, then the full color art over that.

the white prevents paint/ color bleed through on the decals, which can then be pritned thinner, and with higher definition. 

HTH

That make sens.

Thank you