Origin of the Gammadia

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imageRuss Breault writes:

I have run across something interesting and am trying to determine if it has significance.  From the 3rd to the 9th centuries it was apparently common in Byzantine iconography for the outer garments, especially representing people with high authority, to be marked with a stylized "L" called a "Gammadia".  No one seems to know what the origin is but is it possible it is derived from the L-shaped pattern of burns on the Shroud?  These holes when seen on the Lierre copy are very pronounced and for centuries, until the 1532 fire would have been the most obvious marking on the cloth. Was it picked up and turned into a symbol for ancient iconographers?  Would some of your participants like to investigate this further?  Here is an example from Ravenna: