U+1E9B Latin Small Letter Long S with Dot Above

The Wikipedia has the following information about this codepoint:

Ṡ (lowercase: ṡ or ẛ) is a letter of the extended Latin alphabet, formed by S with the addition of a dot above.

In Irish orthography, the dot was used only for ẛ and ṡ, while a following h was used for ch ph th; lenition of other letters was not indicated. Later the two systems spread to the entire set of lenitable consonants and competed with each other. Eventually the standard practice was to use the dot when writing in Gaelic script and the following h when writing in antiqua. Thus ċ and ch represent the same phonetic element in Modern Irish. This is also used to write in Hindustani Music for writing higher Sa also known as C4.