Figure 7.12 Orthographic projection of profile linesF. Oblique Lines
Oblique lines are inclined to all three principal planes:
horizontal, frontal, and profile. An oblique line is not vertical,
parallel or perpendicular to any of the three principal planes,
and therefore does not appear true length in the frontal,
horizontal, or profile views. All three principal views of an
oblique line appear foreshortened.