/* n_1.t:   Conversion of trigraph sequences.   */

/* 1.1: The following 9 sequences are valid trigraph sequences. */
/*  [ ] \ ^ { } | ~ #;  */
    ??( ??) ??/ ??' ??< ??> ??! ??- ??=;

/* 1.2: In directive line.  */
/*  ab | cd;    */
??= define  OR( a, b)   a ??! b
    OR( ab, cd);

/* 1.3: Any sequence other than above 9 is not a trigraph sequence. */
/*  ?? ??? ??% ??^ ?#;  */
    ?? ??? ??% ??^ ???=;