Hi
Looking after the team deciphered the z 340 it is easy to speculate, but, the sequence at the end of cipher Z408: EBEORITEMETEHHPITI,
in a way, wouldn’t that be the tip for the next cipher in your coding ??!
I mean, there are 9 vowel letters and 9 consonant letters, which form TWO distinct groups, that is 9,9,2

Marcelo

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ps:Yes, I know that the TV show was after, but, regardless of the text that he would create, the cipher mode would be this.
Also, it should be noted that it is 18 in length, this is a symbol before the + symbol in 340