Hello, I think (more precisely my compiler thinks [1]) the first line of LB27 is already handled by the new LB22 rule and can be removed. Best, Daniel [1] File "uuseg_line_break.ml", line 206, characters 38-40: 206 | | (* LB27 *) _, (JL|JV|JT|H2|H3), (IN|PO) -> no_boundary s ^^ Warning 12: this sub-pattern is unused.