Canon C2050 Service Handbook page 196

SERVICE MODE
COPIER>ADJUST
<CCD>
Use it to make CCD-related adjustments.
W-PLT-X/Y/Z
Use it to enter the while level data of the standard white plate.
Default Factory setting
A-RG/B-RG
Use it to enter the color displacement correction value (correction depen-
dent on the reader unit) in RG sub scanning direction.
Default Factory setting
A-GB/B-GB
Use it to enter the color displacement correction value (correction depen-
dent on the reader unit) in GB sub scanning direction.
Default Factory setting
AL-RG
Use it to enter the color displacement correction (correction dependent on
the lens of the CCD unit) in RG sub scanning direction.
Default Factory setting
AL-GB
Use it to enter the color displacement value (correction dependent on the
lens of the CCD unit) in GB sub scanning direction.
Default Factory setting
S-54