It has to meet NTSC regulations and specs .
Mainly checking video signal levels and audio. You also check for gamma, blanking, sync and size; 720×480. (HD and Sd signals are different, depends who you are sending it to.)
It needs to be Qc by a video engineer like my self with a vector-scope and the experiance. Some legalizers can do that for you, if you have the budget it will help you a lot. Still go with an eng.
hope that’s helpful for you