The d d (calc-date-notation) command controls the display
of date forms (see section Date Forms). It prompts for a string which
contains letters that represent the various parts of a date and time.
To show which parts should be omitted when the form represents a pure
date with no time, parts of the string can be enclosed in `< >'
marks. If you don't include `< >' markers in the format, Calc
guesses at which parts, if any, should be omitted when formatting
pure dates.
The default format is: `<H:mm:SSpp >Www Mmm D, YYYY'. An example string in this format is `3:32pm Wed Jan 9, 1991'. If you enter a blank format string, this default format is reestablished.
Calc uses `< >' notation for nameless functions as well as for dates. See section Specifying Operators. To avoid confusion with nameless functions, your date formats should avoid using the `#' character.