Variable: ses-completion-keys
ses-completion-keys is a variable defined in ses.el.gz.
Value
("\211" " ")
Documentation
List for keys that can be used for completion while editing.
Source Code
;; Defined in /usr/src/emacs/lisp/ses.el.gz
(defconst ses-completion-keys '("\M-\C-i" "\C-i")
"List for keys that can be used for completion while editing.")