FUNCTION MonthDate RETURNS DATE (INPUT ip-Date# AS DATE, INPUT ip-Months# AS INTEGER).
    DEFINE VARIABLE Day#    AS INTEGER NO-UNDO.
    DEFINE VARIABLE Month#  AS INTEGER NO-UNDO.
    DEFINE VARIABLE Year#   AS INTEGER NO-UNDO.

    /* Do the initial arithmetic */
    ASSIGN Day#   = DAY(ip-Date#)
           Month# = MONTH(ip-Date#) + ip-Months# + YEAR(ip-Date#) * 12
           Year#  = TRUNC((Month# / 12),0)
           Month# = Month# MOD 12.
    IF Month# = 0 THEN Month# = 12.
    
    /* Now check the day for the maximum of the month */
    IF DAY(DATE(3,1,Year#) - 1) = 29 THEN
        /* Leapyear */
        ASSIGN Day# = MINIMUM(INTEGER(ENTRY(Month#,"31,29,31,30,31,30,31,31,30,31,30,31")),Day#).
    ELSE
        /* Normal year */
        ASSIGN Day# = MINIMUM(INTEGER(ENTRY(Month#,"31,28,31,30,31,30,31,31,30,31,30,31")),Day#).
    
    RETURN DATE(Month#,Day#,Year#).
END FUNCTION.

DEF VAR x# AS DATE INITIAL 1/31/01.
DEF VAR y# AS INT INIT -25.
REPEAT WHILE y# < 26:
    DISPLAY x# y# MonthDate(x#,y#).
    ASSIGN y# = y# + 1.
END.