This property defines the Unicodes which are Invisible Stacker
Characters like ္,្,᩠, etc. are listed under Invisible Stacker Indic Syllabic Category.
13 Characters are present in Invisible Stacker Indic Syllabic Category starting with the Unicode point U+1039 that represents the character ္.
Currently, as per latest version 15.0.0, Unicode supports 36 number of Indic Syllabic Category. Here are a few examples - Avagraha,Bindu,Brahmi Joining Number, etc.