This property defines the Unicodes which belongs to CJK Compatibility Ideographs Supplement block
Characters like 丽,丸,乁, etc. are listed under CJK Compatibility Ideographs Supplement Block.
543 Characters are present in CJK Compatibility Ideographs Supplement Block starting with the Unicode point U+2F800 that represents the character 丽.
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.