This property defines the Unicodes which belongs to Control Pictures block
Characters like ␀,␁,␂, etc. are listed under Control Pictures Block.
40 Characters are present in Control Pictures Block starting with the Unicode point U+2400 that represents the character ␀.
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.