This property defines the Diacritic Unicodes which can be present at Overstruck of the base character
Characters like ᳔,᳢,᳣, etc. are listed under Overstruck Indic Positional Category.
10 Characters are present in Overstruck Indic Positional Category starting with the Unicode point U+1CD4 that represents the character ᳔.
Currently, as per latest version 15.0.0, Unicode supports 15 number of Indic Positional Category. Here are a few examples - Bottom,Bottom And Left,Bottom And Right, etc.