The vector scope tool is displayed when a stereo input is detected, otherwise the display will switch to Surround scope provided if your edition of Pure Analyzer includes this option.
Vector scope display in stereo.
Vector scope display in surround (with selection menu).
L-R
Use only Left and Right Channels.
Front
Use a stereo down mix with all front channels.
Rear
Use a stereo down mix with all Rear channels.
Stereo downmix
Use a stereo down mix with all channels.
Lt/Rt downmix
Use a Lt/Rt down mix with all channels.
LR-Lfe
Use a mono summation of Left and Right + the Lfe (sub) channel.
Center-Lfe
Use Center + Lfe (sub) channel.
Front-Lfe
Use a mono summation of the front channels + the Lfe (sub) channel.