What is proper NTSC fps for BlankClip()?

[FredThompson]

One of the arguments for BlankClip() is the fps. What is the exact value for proper NTSC?

I'm confused by the documentation. The funtion parameters include length, height, width, and fps, among others. Width and height I understand. What is the difference between length and fps?

[Kika]

Lenght specifies, how long in Frames the Clip will be.
If you set fps to 29.97 and lenght to 29.97, the Clips will have a Playtime of one second. For a three second clip, set lenght to 89.91.

You can also set fps to 23.976 (Film-Mode), then use 23.976 on lenght for a one second long clip, 47.952 for two seconds and so on.

[FredThompson]

I had a hunch length was number of frames. Thanks.

Thing is, I've watched VirtualDub get real snotty about framerates. It seems to compare the byte value, not calculate frame rate. That's why I'm wondering about the exact fps value.

However, for the intended use right now, length is what I need.

Thanks again for the help.