This property defines the Unicodes which belongs to Combining Diacritical Marks For Symbols block
Characters like ⃐,⃑,⃒, etc. are listed under Combining Diacritical Marks For Symbols Block.
34 Characters are present in Combining Diacritical Marks For Symbols Block starting with the Unicode point U+20D0 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.