This property defines the Diacritic Unicodes which can be present at Top of the base character
Characters like ऀ,ँ,ं, etc. are listed under Top Indic Positional Category.
428 Characters are present in Top Indic Positional Category starting with the Unicode point U+0900 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.