When using NukeStudio or Hiero, you may come across the frame rate setting of 23.98 frames per second.
As footage may sometimes be captured at 23.976 frames per second, this article answers the question of whether there is a difference between these two frame rate settings.
23.98 and 23.976 refer to the same NTSC standard 24000/1001, with 23.976 being rounded to one more digit of precision.
The actual frame rate value used internally is 23.976, or rather 24000/1001 to get as close to the actual value of 23.9760239760... as possible.
This is the same way the ITU broadcast recommendations specify these NTSC frame rates (a "fractional" rate of 24 divided by 1.001, as referred to in e.g. ITU-R BT.709 p. 2).
The number has been rounded to 23.98 for the label in the UI only, following the lead of other applications such as Final Cut Pro. This screenshot shows the frame rate setting as displayed in NukeStudio and Hiero's UI: