Attenuators aka Pads...
http://www.dplay.com/book/pgs2e/pads.pdf
All about Pads...
Uneeda Audio - Build your own attenuator pads
Resistor Values for T & H Type Attenuation...
T-Pad / H-Pad Calculator - Resistor Values for Attenuation
If anyone is interested...
I have an Excel file that calculates T, O, H, Pi, L and U type attenuators.
Since I cannot upload Excel files PM me your email address and (if I'm in a good mood) I will send you my attenuator calculator just for the asking.