In a few different places (1) (2), ORACC lists Ś (S with acute accent, U+015A) as a Unicode character used for Sumero-Akkadian cuneiform transcription.
However, I've never seen this letter used (in ORACC or anywhere else), and am not sure what it would mean—to my knowledge, Sumero-Akkadian cuneiform only ever distinguished four sibilants (S Z Ṣ Š), and even those had some overlap between them.
So, what is this Ś in Sumero-Akkadian cuneiform?
(P.S. I know the letter Ś is sometimes used in transcribing Ugaritic cuneiform, and in discussions of Proto-Semitic, but if ORACC wanted to cover those they'd need a whole lot more glyphs in their Unicode tables: Ḥ, Ġ, etc. It seems notable that this is the only glyph in 1 that I don't recognize from either Sumerian or Akkadian.)