Tsumagari (2010:51) compares Ainu san 'shelf' with Uilta saan 'shelf for drying fish' and reports corresponding words in Ulch, Nanai, and Negidal without printing their forms. He derives Nivkh č’aŋ from an s-initial Ainu or Tungusic source. The Ainu–Uilta direction remains unresolved. Tangiku (2018) marks the Ainu comparison uncertain.