Touring the Interface with a Basic Composite - Nuke 101: Professional Compositing and Visual Effects - page 62

You can pick color with the RGB, HSV, and TMI sliders. By default, only the HSV and
RGB sliders are available, but the TMI button at the top of the color wheel will display
the TMI sliders.
1. Click the Color picker button for Grade1's Gamma property.
2. Go ahead and play with the color wheel. When you're finished, close it.
Notice you no longer have a slider. Instead, you have four numeric fields ( FIGURE 2.30 ) .
Figure 2.30. Your single Gamma slider turned into four numeric fields.