This property defines tahe Unicodes which are Cluster Break between characters that have a break opportunity between them.
Characters like ,,, etc. are listed under Prefix Grapheme Cluster Break.
27 Characters are present in Prefix Grapheme Cluster Break starting with the Unicode point U+0600 that represents the character .
Currently, as per latest version 15.0.0, Unicode supports 14 number of Grapheme Cluster Break. Here are a few examples - Base,Carriage Return,Control Neutral, etc.