This command applies to timeseries where data are composed of dates/times. It has no meaning unless the command `set xdata time` is given also. Syntax: set timefmt "<format string>" show timefmt The string argument tells `gnuplot` how to read timedata from the datafile. The valid formats are: Format Explanation %d day of the month, 1--31 %m month of the year, 1--12 %y year, 0--99 %Y year, 4-digit %j day of the year, 1--365 %H hour, 0--24 %M minute, 0--60 %S second, 0--60 %b three-character abbreviation of the name of the month %B name of the month Any character is allowed in the string, but must match exactly. \t (tab) is recognized. Backslash-octals (\nnn) are converted to char. If there is no separating character between the time/date elements, then %d, %m, %y, %H, %M and %S read two digits each, %Y reads four digits and %j reads three digits. %b requires three characters, and %B requires as many as it needs. Spaces are treated slightly differently. A space in the string stands for zero or more whitespace characters in the file. That is, "%H %M" can be used to read "1220" and "12 20" as well as "12 20". Each set of non-blank characters in the timedata counts as one column in the `using n:n` specification. Thus `11:11 25/12/76 21.0` consists of three columns. To avoid confusion, `gnuplot` requires that you provide a complete `using` specification if your file contains timedata. Since `gnuplot` cannot read non-numerical text, if the date format includes the day or month in words, the format string must exclude this text. But it can still be printed with the "%a", "%A", "%b", or "%B" specifier: see `set format` for more details about these and other options for printing timedata. (`gnuplot` will determine the proper month and weekday from the numerical values.) See also `set xdata` and Time/date for more information. Example: set timefmt "%d/%m/%Y\t%H:%M" tells `gnuplot` to read date and time separated by tab. (But look closely at your data---what began as a tab may have been converted to spaces somewhere along the line; the format string must match what is actually in the file.)