BEGIN

    BOOLEAN PROCEDURE ISNUMERIC(W); TEXT W;
    BEGIN
        BOOLEAN PROCEDURE MORE;
            MORE := W.MORE;
        CHARACTER PROCEDURE NEXT;
            NEXT := IF MORE THEN W.GETCHAR ELSE CHAR(0);
        CHARACTER PROCEDURE LAST;
            LAST := IF W.LENGTH = 0
                    THEN CHAR(0)
                    ELSE W.SUB(W.LENGTH,1).GETCHAR;
        CHARACTER CH;
        W.SETPOS(1);
        IF MORE THEN
        BEGIN
            CH := NEXT;
            IF CH = '-' OR CH = '+' THEN CH := NEXT;
            WHILE DIGIT(CH) DO CH := NEXT;
            IF CH = '.' THEN
            BEGIN
                CH := NEXT;
                IF NOT DIGIT(CH) THEN GOTO L;
                WHILE DIGIT(CH) DO CH := NEXT;
            END;
            IF CH = '&' THEN
            BEGIN
                CH := NEXT;
                IF CH = '-' OR CH = '+' THEN CH := NEXT;
                WHILE DIGIT(CH) DO CH := NEXT;
            END;
        END;
    L:  ISNUMERIC := (W.LENGTH > 0) AND THEN (NOT MORE) AND THEN DIGIT(LAST);
    END;

    REAL X;
    TEXT T;
    FOR X := 0, -3.1415, 2.768&+31, 5&10, .5, 5.&10 DO
    BEGIN
        OUTREAL(X, 10, 20);
        OUTIMAGE;
    END;

    OUTIMAGE;

    FOR T :- "0", "-3.1415", "2.768&+31", ".5", "5&22" DO
    BEGIN
        OUTTEXT(IF ISNUMERIC(T) THEN "    NUMERIC " ELSE "NOT NUMERIC ");
        OUTCHAR('"');
        OUTTEXT(T);
        OUTCHAR('"');
        IF T = "0" THEN OUTCHAR(CHAR(9)); OUTCHAR(CHAR(9));
        COMMENT PROBE ;
        X := T.GETREAL;
        OUTREAL(X, 10, 20);
        OUTIMAGE;
    END;

    OUTIMAGE;

    X := 5.&10;
   !X := 5&;
   !X := 5.;
    X := .5;
    FOR T :- "", "5.", "5&", "5&+", "5.&", "5.&-", "5.&10" DO
    BEGIN
        OUTTEXT(IF ISNUMERIC(T) THEN "    NUMERIC " ELSE "NOT NUMERIC ");
        OUTCHAR('"');
        OUTTEXT(T);
        OUTCHAR('"');
        OUTIMAGE;
    END;

END