fifo ofif 들어갑니다.

\def\fifo{\afterassignment\tap\let\nxt= }

\def\tap{\ifx\nxt\ofif\ofif\fi\process\nxt\fifo}

\def\ofif#1\fifo{\fi}

\def\process#1{\ifx#1.dot\else\ifx#1?QM\else#1\fi\fi}

\def\segment#1{\fifo #1\ofif}