- The serial number of the letter in its file shall also be marked in red ink on the docket of each letter, i.e. the first letter received or issued on a file shall be marked S. No. 1, the second letter received or issued be marked S. No. 2 and so on.When a letter is received or issued if it pertains to a previously existing file, the file shall be got out, and the next consecutive serial number of the series of that file shall be assigned to the letter.
