To indicate within the descriptive text the composition of the serial number, the following alphanumeric characters are generally used: A: any letter, N: any digit: e.g. <> , <> or
<>. Other letters are normally only used if the same letter is actually printed on each document of the same series (version) - then it is put between quotation marks: e.g.: < "Nr EE" NNNNNN >:
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