It is very similar to the PAL tv norm, however, the U.S. broadcast standard has some odd appendages that you need to be aware of.
All analog television sets sold in the United States actually display something less than the entire picture as broadcast. The amount of picture that is cropped out (by overscan of the electron gun OR masking by the frame that holds the tube in place at the front of the cabinet) can be as much as a full 10% from EACH SIDE (including top and bottom)!
People creating NTSC DVD's which are likely to be played on analog (non LCD, as in plain old CRT, aka picture tube sets...) Should use this option when transcoding:
In all cases, this will cause more of the picture to be visible, and in the case of subtitled material it will prevent the subtitles from being chopped off partly or entirely.
Note that doing this will NOT produce black borders around the edge of the screen unless your television is adjusted to underscan, which is exceedingly rare.
-j -16,-32,16,-32 might appear to be a better choice, because it will generally allow the "fast" option to -Z to work properly by preserving modulo 8 resolution (assuming the source is mod 8). However, I have found that, in practice, the values -j -18,-34,-22,-34 are closer to the correct values for analog overscan, and also seem to reduce the intensity of interlacing artifacts.
Perhaps the resizing not on mod 8 boundaries introduces gaussian noise as a side effect? In any case, it produces a better viewing experience.
This page explains overscan with examples: http://www.mastersofcinema.org/reviews/03lookingbeyond.htm