RGB / RGB 4:4:4

The RGB color model is an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green and blue.
Note that 4:4:4 may instead be referring to RGB color space, which implicitly does not have any chroma subsampling at all. RGB 4:4:4 signals can be recorded over dual-link HD SDI.