3 of 3 added link / reference info

What does the /shin/ marker (like Petucha/Setuma) at the end of Torah books mean?

I've been reading about details of Torah sofrut, and after learning about the paragraph markers peh / פ (petucha) and samekh / ס (setuma), I noticed some similarly placed shin markers (mostly at the end of a sefer), but cannot find an answer in Google searches. What does it stand for? (Example: parsha VaYechi). I'm using an electronic version from Mechon Mamre similar to Keter Yerushalayim / Aleppo Codex.