: _ilen ( length of str in IBUF )
    IBUF BEGIN C@+ EOL? UNTIL IBUF - 1- ;
: I
    IBUF _type EDPOS @ 64 /MOD ( cno lno )
    1+ 64 * _cpos ( cno next-line-ptr )
    SWAP 63 -^ _ilen ( nlp nb-of-chars-to-move ilen )
    2DUP > IF
        SWAP OVER - 1+ ( nlp ilen nbc ) 0 DO ( a ilen )
            SWAP 1- 2DUP -^ ( ilen a-1 a-ilen-1 ) C@ OVER C!
            SWAP ( a ilen )
        LOOP
    ELSE DROP ( ilen becomes nbc )
    THEN
    SWAP DROP DUP IBUF EDPOS @ _cpos ROT MOVE ( ilen )
    EDPOS +! EDPOS @ 64 / _pln
;