Measurement methods for placement of the F3, F4, P3, and P4 points differ. If measured front-to-back (Fp1-F3-C3-P3-O1 and Fp2-F4-C4-P4-O2 montages), they can be 25% "up" from the front and back points (Fp1, Fp2, O1, and O2).
Different placement measurement approaches are used for the F3, F4, P3, and P4 points. When evaluated from a frontal-to-rear perspective (e.g., Fp1-F3-C3-P3-O1 and Fp2-F4-C4-P4-O2 layouts), these points can be 25% higher than their corresponding front and back anchors (Fp1, Fp2, O1, and O2).