This property defines the Unicodes which belongs to Old Sogdian block
Characters like 𐼀,𐼁,𐼂, etc. are listed under Old Sogdian Block.
41 Characters are present in Old Sogdian Block starting with the Unicode point U+10F00 that represents the character 𐼀.
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.