This property defines the Unicodes which are Spacing Combining Marks
Characters like ः,ऻ,ा, etc. are listed under Spacing Combining Mark General Category.
452 Characters are present in Spacing Combining Mark General Category starting with the Unicode point U+0903 that represents the character ः.
Currently, as per latest version 15.0.0, Unicode supports 30 number of General Category. Here are a few examples - Close Punctuation,Connector Punctuation,Control Character, etc.