This property defines the Unicodes which belongs to Latin Extended Additional block
Characters like Ḁ,ḁ,Ḃ, etc. are listed under Latin Extended Additional Block.
256 Characters are present in Latin Extended Additional Block starting with the Unicode point U+1E00 that represents the character Ḁ.
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.