table-word-continuation-char

table-word-continuation-char is a variable defined in `table.el'.
Its value is

92

Documentation:
Character that indicates word continuation into the next line.
This character has a special meaning only in the fixed width mode,
that is when `table-fixed-width-mode' is non-nil . In the fixed width
mode this character indicates that the location is continuing into the
next line. Be careful about the choice of this character. It is
treated substantially different manner than ordinary characters. Try
select a character that is unlikely to appear in your document.

You can customize this variable.