Date Notes.
CS-Date Notes are FSNs that signify a date. M 03 11 1989 M would represent March 11, 1989.
The above date of March 11, 1989, covers a lot of different “types” of date Notes.
Type 1: It is a Note with a date of special significance only to an individual collector, such as the date they got married, started a business, etc.
Type 2:It is also a CS-Birthday Note, this is special to someone with that birthday or a collector with someone they know that has that date as their birthday.
Type 3: It is a date with significance, March 11th 1989 was the premiere of the T. V. show “Cops”.
While a specific date note may not be as easy to sell to everyone in the collecting community, to a specific collector, it can have a high premium. CS-Birthday Notes sell pretty often at $35 - $40 over face value but may take a while for the right person to come along.
While a date Note with a decent date in history, such as Nov. 1, 1872, M 11 01 1872 M, the day that Susan B. Anthony registered to vote. This Note can be of higher significance to many diverse types of collectors. Those interested in history, women’s rights, women’s suffrage, Susan B. Anthony, constitutionals, anti-establishment, and so on. Taking a quick minute or two and researching the CS-Date Note you have found to see what item of importance happened on that day can be worth it.

Some examples: Dec. 25, 1776, M 12 25 1776 M, the day that George Washington crossed the Delaware.
Aug. 28, 1963, M 08 28 1963 M, Martin Luther King Jr. delivers his “I Have a Dream” speech.
Sept. 9, 1965, M 10 09 1965 M, the day baseball player Sandy Koufax threw a perfect game.

CS-Date Notes, CS-Birthday Notes, CS-History Notes and CS-Future Notes.

While all CS-Date Notes can be CS-Birthday Notes and CS-History Notes at the same time, to make things easier the way that Currency-Systems identifies CS-Date Notes are as follows:
1: CS-Birthday Notes are Notes that the person with the birthday can hold while alive, the formula for this is a date range between: Today’s date minus 100 years. E.g., M 12 25 2021 M, Christmas Day 2021.
2: CS-History Notes are Notes that are Today’s date minus 100 years and earlier.
3: CS-Future Notes are Notes with date in the future from today’s date, M 12 25 2050 M.

CS-Leap Year Notes
are quite a bit rarer than CS-Birthday Notes and CS-History Notes as they only occur on one day, February 29, every 4 years: 1996, 2000, 2004, 2008, 2012, 2016, 2020, 2024, etc. Feb. 29, 2000 = M 02 29 2000 M. The formula to determine a Leap Year Note is as follows:
1: Must have the Month and Day of Feb. 29, M 0229xxxx M.
2: Starting with year 0000 it occurs every 4 years except for years divisible by 100, unless the year is also divisible by 400. So, 1800, 1900, and 2100 are not leap years, but 2000 is a leap year.

Now that the basics have been discussed, let’s take it one step further with how dates are used.
There are three basic ways that dates are used worldwide, and this is how Currency-Systems uses them:
Type 1: mm/dd/yyyy = U.S. (United States date format) M mmddyyyy M.
Type 2: dd/mm/yyyy = E.U. (European date format) M ddmmyyyy M.
Type 3: yyyy/mm/dd = INTL. (International date format) M yyyymmdd M.

CS-Reverse Date Notes.
A CS-Reverse Date Note is when a CS-Date Note is read backwards i.e. M 12 25 1975 M is reversed to read M 5791 52 21 M. The numismatic community as a whole has not embraced these notes, and since desirability is so low, there is no real premium added to these notes, however the “eye of the beholder” applies to certain people who would attach significance to the notes.
CS-U.S. Date Notes.
CS-U.S. Birthday Note.
In a CS-U.S. Birthday Note the date must be in the order mm/dd/yyyy, M 11221975 M = 11/22/1975 = Nov. 22, 1975.

CS-U.S. Leap Year Birthday Note.
In a CS-U.S. Leap Year Birthday Note the date must be in the order mm/dd/ yyyy, must start with Feb. 29th, and the year must be a leap year, and the year can be no older than 100 years.
M 02292000 M = 02/29/2000 = Feb. 29, 2000.

CS-U.S. History Note.
In a CS-US History Note the date must be in the order mm/dd/yyyy, and the year must be older than 100 years from today’s date. M 01091900 M = 01/09/1900 = Jan. 9, 1900.

CS-U.S. Leap Year History Note.
In a CS-US Leap Year History Note the date must be in the order mm/dd/yyyy, must start with Feb. 29th, the year must be a leap year, and the year must be older than 100 years. M 02291900 M = 02/29/1900 = Feb. 29th 1900.

CS-U.S. Future Date Note.
In a CS-U.S. Future Date Note the date must be in the order mm/dd/yyyy and must represent a date in the future. M 12252040 M = 12/25/2040 = Dec. 25, 2040.

CS-E.U. Date Notes

CS-E.U. Birthday Note.
In a CS-E.U. Birthday Note the date must be in the order dd/mm/yyyy. M 22111975 M = 22/11/1975 = 22 Nov. 1975.

CS-E.U. Leap Year Birthday Note.
In a CS-E.U. Leap Year Birthday Note the date must be in the order dd/mm/ yyyy, must start with Feb. 29th, the year must be a leap year, and the year can be no older than 100 years from today’s date. M 29022000 M = 29/02/2000 = 29 Feb. 2000.

CS-E.U. History Note.
In a CS-E.U. History Note the date must be in the order dd/mm/yyyy and the year must be older than 100 years. M 15011900 M = 15/01/1900 = 15 Jan. 1900.

CS-E.U. Leap Year History Note.
In a CS-E.U. Leap Year History Note the date must be in the order dd/mm/yyyy, must start with Feb. 29th, the year must be a leap year, and the year must be older than 100 years. M 29021900 M = 29/02/1900 = 29th Feb. 1900.

CS-E.U. Future Date Note.
In a CS-E.U. Future Date Note the date must be in the order dd/mm/yyyy and must represent a date in the future. M 25122040 M = 25/12/2040 = 25 Dec. 2040.

CS-INTL. Date Notes.
CS-INTL. Birthday Note. In a CS-INTL. Birthday Note the date must be in the order yyyy/mm/dd. M 19751122 M = 1975/11/22 = 1975 Nov. 22.

CS-INTL. Leap Year Birthday Note.
In a CS-INTL. Leap Year Birthday Note the date must be in the order yyyy/mm/ dd, must end with Feb. 29th, the year must be a leap year, and the year can be no older than 100 years from today’s date. M 20000229 M = 2000/02/29 = 2000 Feb. 29.

CS-INTL. History Note.
In a CS-INTL. History Note the date must be in the order yyyy/mm/dd and the year must be older than 100 years from today’s date. M 19000109 M = 1900/01/09 = 1900 Jan. 9.

CS-INTL. Leap Year History Note.
In a CS-INTL. Leap Year History Note the date must be in the order yyyy/mm/ dd, must start with Feb. 29th, the year must be a leap year, and the year must be older than 100 years from today’s date. M 19000229 M = 1900/02/29 = 1900 Feb. 29.

CS-INTL. Future Date Note.
In a CS-INTL. Future Date Note the date must be in the order yyyy/mm/dd and must represent a date in the future. M 20401225 M = 2040/12/25 = 2040 Dec. 25.

CS-True Year Note.
A CS-True Year Note is a Note that contains only a year that is grouped together and contains a CS-4OAK of zeros, M 00019750 M. Note: The standard practice for years is that they contain 4 digits, i.e. 0001, 0999, 1001, 200, 2022, etc.

CS-Numbered Year Note.
A CS-Numbered Year Note is a Note that contains a year that is grouped together and contains a CS-4OAK of a number other than zero, M 22197522 M

CS-Random Year Note.
A CS-Random Year Note is a Note that contains a year that is grouped together with random numbers.

CS-Year Notes.
CS-Year Notes are FSNs that contain years, the basic rule is that there is only a single year or that multiple years must take up all the digit spaces i.e. M 2000 2021 M if they do not, it should not be counted as a true year note M x200 2021 M or M 9200 2021 M.
Note: The standard practice for years is that they contain 4 digits, i.e. 0001, 0999, 1001, 200, 2022, etc.

CS-Double Year Note.
A CS-Double Year Note contains two years which are not intermingled and take up all the digits in the serial number. The first year starts at position 1 and goes to position 4. The second year starts at position 5 and goes to position 8, M 1975 1989 M.

CS-Triple Year Note.
A CS-Triple Year Note is a Note that contains three years, M 19192012 M. In this example there are three years: 1919,1920, and 2012. The first year starts at position 1, the second year can start at positions 2, 3, or 4, and the third year starts at position 5.

CS-Quad Year Note.
A CS-Quad Year Note contains four years, M 11192010 M. In this example there are four years: 1119,1192,1920, and 2010. The first year starts at position 1 and goes to position 4, the second year can start at positions 2 or 3, the third year can start at position 3 or 4, and the fourth year starts at position 5.

CS-Quint Year Note.
A CS-Quint Year Note contains five years, M 11112010 M. In this example there are five years: 1111, 1112, 1120, 1201, and 2010. The first year starts at position 1, the second year starts at position 2, the third year starts at position 3, the fourth year starts at position 4, and the fifth year starts at position 5.

CS-Day Notes.
In CS-Day notes there is a month and a day that are grouped together within the FSN, M 00122500 M. This would represent Christmas Day, 12/25, Dec. 25th. Formats: U.S. mm/dd, E.U. dd/mm, INTL. mm/dd.

CS-True Day Note.
A CS-True Day Note is a Note that contains a day and month grouped together and a CS-4OAK of zeros, M 00112500 M, would be Nov. 25th, while M 00123000 M would be Jan. 23rd and Dec. 30th! M x0123xxx M and M xx1230xx M respectively.

CS-U.S. and INTL. True Day Notes.

CS-U.S. True Day Notes and CS-INTL.
True Day Notes contain a month, a day, and zeros, M 01125000 M. The day and month must be grouped together, and the month must come before the day (mm/dd). The U.S. and INTL. Notes use this date format.

CS-E.U. True Day Notes.
CS-E.U. True Day Notes contain a month, a day, and zeros, M 02511000 M. The day and month must be grouped together, and the day must come before the month (dd/mm). The E.U. Note uses this date format.

CS-Numbered Day Note.
A CS-Numbered Day Note is a Note that contains a month and day grouped together and a CS-4OAK of a number that is not a zero, M 44112544 M. These can be U.S., E.U., or INTL. date formats.

DCS-Random Day Month Note.
A CS-Random Day Month Note is a Note that contains a month and day grouped together and also contains four random numbers, M xx1125xx M. These can be U.S., E.U., or INTL. date formats.

Note: This page contains excerpts and basic information from the book "The Green Guide to Fancy Serial Numbers". Please consider adding a copy to your library, thank you.