How to: Create custom date formats.
Solution:
Select 'Cells...' from the 'Format' menu to display the 'Format Cells' dialog box, click the 'Number' tab, and create the desired format based on a predefined date format.
1) Select the cells to format.
2) Select the 'Format' menu and select 'Cells...'. (The Format Cells dialog box appears.)
3) Click the 'Number' tab.
4) Select 'Date' from the 'Category' list box. (All built-in date formats appear on the right.)
5) Select the date format that most closely resembles the format to be created.
6) Select 'Custom' from the 'Category' list box. (The code for the selected format appears in the Type box.)
7) Modify the format code to create the desired format in the 'Type' box.
Modifying the code
NOTE: Modifying a built-in format does not remove or change the original format.
8) Click 'OK' to save the change and close the 'Format Cells' dialog box.