Rec 709 (BT709, sRGB)
ITU-R Recommendation BT.709, more commonly known by the abbreviations Rec. 709 or BT.709, standardizes the format of High- Definition television, having 16:9 (widescreen) aspect ratio. The first edition of the standard was approved in 1990. Even of slightly different sRBG and Rec709 gamuts are almost identical.
The 3 triangles show the large color space proposed by Rec. 2020 (New standard for UltraHD TVs. Only currently available on laser projectors), the smaller DCI-P3 color space (Digital Cinema, coming to TVs), and the smallest Rec 709 space (traditional video monitors - Broadcast TV, Blu-ray, Over-The-Top).