set-char-table-range

set-char-table-range is a built-in function in `C source code'.

(set-char-table-range CHAR-TABLE RANGE VALUE)

Set the value in CHAR-TABLE for a range of characters RANGE to VALUE.
RANGE should be t (for all characters), nil (for the default value),
a cons of character codes (for characters in the range),
or a character code. Return VALUE.