SVM stands for Scanning Velocity Modulation. Some manufacturers leave of the S and just call it VM. It's generally touted as a "feature" that makes the picture "crisper" but all it really does is cause a hideous amount of ringing and an unnatural picture. The ability to turn it off, either through the TV's main menu or the service menu, is the real "feature" if you care about an accurate picture.
SVM stands for Scan Velocity Modulation. Basically, what it does is vary (modulate) the speed of the scan during the time it takes for the electron gun to scan the tube from the left side of the picture to the right side of the picture. If the picture is bright in an area, it slows the scan down, if it is dark it speeds the scan up. This results in the picture appearing brighter without the manufacturer having to spend any money on a beefier power supply. The side effects are blurry transitions, a loss of fine detail, and geometric distortions. To cover up the blurry transitions, they put a peaking circuit in to "enhance" edge transitions and this results in the halo effect. There is no place for SVM in high fidelity imaging.