This is a "by the years" table that illustrates what dates can be substituted. The ones in black are already programmed into the SL-HF2100. To fool the clock/timer enter a date from a past year using the corresponding letter for a future year (past 2005). As you can see the numbers in red do not have any match. Unfortunately for those years you will not be able to make a year substitution. You will still be able to fool the clock by using the day of the week, but the year will not match. In many cases the year will not carry over to January 1st.

2011 - D

2019 - K