Going through the letters A to F represents increasing temperature and/or increasing altitude.
If we take 45000 Kg with flap 5 we have the following figures
A V1 121 VR 123 V2 136
B V1 122 VR 124 V2 135
C V1 122 VR 125 V2 135
D V1 124 VR 126 V2 135
E V1 125 VR 127 V2 134
F V1 128 VR 128 V2 134
Although there are some flat areas, the general trend is V1 and VR increasing while V2 decreases.