The 'Rectifier Keys' are as follows:

SE = Single ended, only one power supply voltage is generated. 
BP = Bipolar (not the disorder), it means two voltages of opposite polarities are generated. 
HW = half wave, only one camel hump 
FW = Full Wave, two camel humps 
WTF = you know this one 
BR = bridge rectifier 
VD = not what you think, but would you believe Voltage Doubler?