Quote Originally Posted by sremick
How so? Please explain.

Particularly curious since there's a 50 Hz version of PAL and a 60 Hz version of PAL.

NTSC and PAL are color-coding technologies. These signals are analog and have an inherent vertical refresh rate of 50 Hz or 60 Hz (PAL can be either). The vertical refresh rate is independent of the mains AC frequency.

If you need further proof, just look here:

http://upload.wikimedia.org/wikipedi..._frequency.png

compared to:

http://upload.wikimedia.org/wikipedi...-SECAM.svg.png

In particular, note Greenland, Burma, lower Japan, and parts of South America.
There's also 100hz on newer TV's