Monogram Initial

Monograms? What is the conventional format for a three-letter monogram?

This may sound dumb, but I do not know how one sets up a three-letter monogram. I am talking about the monograms where the middle letter is larger than the letter on the left and on the right. For example, with that kind of monogram would Jane K. Doe’s monogram be JKD (where the K is larger) or JDK (where the D is larger). It seems odd that the largest letter would be the one that is the middle initial of one’s name, but I just do not know how this works. Thanks in advance!

If the name was Jane K. Doe then the monogram would be JDK

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