In the upper case Roman alphabet they are: C, I, J, O and S. However, in the case of C, O and S, there are parts of the curved segments which are parallel.
The answer depends on the font being used. In a serif font a lot more characters will have intersecting lines. So the answer is likely to be a subset of the upper case sans serif letters C, I , J, O, S. But even here, the letter O does have parallel segments, and possibly C as well.
Letters that have parallel line segments are H, E, F, M, and N
W
There are letters in the alphabet with both parallel and perpendicular lines. In alphabetical order, they are E, F, and H. If the joining point can be considered perpendicular and parallel, then B, D, P, and R also match the criterion.
Parallel: E, F, H, I, M, N, O (in some fonts), U, Z. Perpendicular: E, F, G, H, L, T. Many more letters have perpendicular lines in serif fonts. Also, there are letters, such as D, in which the ends of the curved section are parallel to one another and are perpendicular to the vertical element.
The answer depends on the font being used. In a serif font a lot more characters will have intersecting lines. So the answer is likely to be a subset of the upper case sans serif letters C, I , J, O, S. But even here, the letter O does have parallel segments, and possibly C as well.
t
25 o because sOme of them are perpendicular
The letter - H
In upper case: AKVXY In lower case: klvxy
Yellow
I
Letters that have parallel line segments are H, E, F, M, and N
E
W
The letters A, K, M, N, R, V, W, Y, and Z all have lines in them that are not perpendicular.
There are letters in the alphabet with both parallel and perpendicular lines. In alphabetical order, they are E, F, and H. If the joining point can be considered perpendicular and parallel, then B, D, P, and R also match the criterion.