Wing coding Bf110 and in general

[carlmu]

From pictures showing the Bf110 from below, many, but not all, show a letter lateral to the Balkenkreuz. As far as I can see, this letter is the third of the four in the code marking. So, if this letter is say K, the fuselage coding would be **-K*?
Not very familiar with the code letter system, I do not know why not all planes had this underwing letter. If the wing had this letter, was the letter the same on both sides?