This property defines the Unicodes which belongs to Greek block
Characters like Ͱ,ͱ,Ͳ, etc. are listed under Greek Block.
140 Characters are present in Greek Block starting with the Unicode point U+0370 that represents the character Ͱ.
Currently, as per latest version 15.0.0, Unicode supports 328 number of Block. Here are a few examples - Latin Extended E,Adlam,Aegean Numbers, etc.