For details, Google Date Manpage
Right mouse-click then select Properties
The Clock Custom Format “%r, %d %b” will display hh:mm:ss AM/PM, dd Month, e.g.: 10:34:51 PM, 23 Mar
The Tooltip Custom Format:
- “%A %d %B %Y” will display Day-of-week dd Month Year, e.g.: Friday 23 March 2010
- “%a %d %b %r” will display Day-of-week Day-of-month Month-abbr and hh:mm:ss AM/PM
- “%a %d %b %H:%M” will display Day-of-week Day-of-month Month-abbr and hh:mm