Brain Game: 9 Letters, No Stamps

What do these nine letters of the alphabet have in common?

B, D, F, H, I, J, K, L, T

HERE is the solution.

THE ANSWER:

When written in lower case, these nine letters have "ascenders" that rise above the baseline. Likewise, the letters G, J, P, Q and Y dip below the baseline when written in lower case.