This ostracon is important for the study of the Coptic Cryptography because it contains a clear evidence for what we can call ‘A Key’ for the scribe rendered the original letter over its cryptographical equivalent. As far as I know, this ostraca is unique, for only about thirty published examples of Coptic cryptography texts have been recorded until now as had been mentioned above, and no one of them holds this ‘Key’ by this form, but further studies and publications in this field will reveal other texts like this ‘Key’ because this type of text served as an exercise by the writer to himself or to someone in order to memorize the alphabets in their Crypto-graphical form.
And here is the picture of the Key on the ostracon, showing the characters and their assigned values:
This is precisely the type of thing that I'm talking about that the Kirtland Egyptian Papers (KEP) and the Explanations for the Facsimiles represent: Keys that show meaning assignments. I believe that the KEP and the Explanations are reconstructions of ancient keys that were had by ancient people, and that they contain real, ancient information that was not made up by Joseph Smith. And the ancient versions of these documents are no longer extant. That is why I say, the only actual, ancient Egyptian material that was ever in the hands of Joseph Smith was the Sensen Papyrus, the Hypocephalus, pieces of the Book of the Dead, and other materials. He never had an Egyptian original for the Book of Abraham or the Book of Joseph. He reconstructed an ancient KEY for the Sensen Papyrus, that demonstrates how the Sensen Papyrus was used with the story of the Book of Abraham. The Sensen material never contained the text of the Book of Abraham. Joseph Smith never had a papyrus that contained the text of the Book of Abraham. It is true that Abraham wrote down that text in ancient times, but Joseph Smith never had that kind of document.