This property defines the Unicodes which belongs to Modifier Letters block
Characters like ʰ,ʱ,ʲ, etc. are listed under Modifier Letters Block.
80 Characters are present in Modifier Letters Block starting with the Unicode point U+02B0 that represents the character ʰ.
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.