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][1] similar to Keter Yerushalayim / Aleppo Codex.

  [1]: http://www.mechon-mamre.org/p/pt/pt0150.htm