In time/date mode, the acceptable formats are:
Format Explanation
%a abbreviated name of day of the week
%A full name of day of the week
%b or %h abbreviated name of the month
%B full name of the month
%d day of the month, 1--31
%D shorthand for "%m/%d/%y"
%H or %k hour, 0--24
%I or %l hour, 0--12
%j day of the year, 1--366
%m month, 1--12
%M minute, 0--60
%p "am" or "pm"
%r shorthand for "%I:%M:%S %p"
%R shorthand for %H:%M"
%S second, 0--60
%T shorthand for "%H:%M:%S"
%U week of the year (week starts on Sunday)
%w day of the week, 0--6 (Sunday = 0)
%W week of the year (week starts on Monday)
%y year, 0-99
%Y year, 4-digit
Except for the non-numerical formats, these may be preceded by a "0" ("zero", not "oh") to pad the field length with leading zeroes, and a positive digit, to define the minimum field width (which will be overridden if the specified width is not large enough to contain the number). There is a 24-character limit to the length of the printed text; longer strings will be truncated.
Examples:
Suppose the text is "76/12/25 23:11:11". Then
set format x # defaults to "12/25/76" \n "23:11"
set format x "%A, %d %b %Y" # "Saturday, 25 Dec 1976"
set format x "%r %d" # "11:11:11 pm 12/25/76"
Suppose the text is "98/07/06 05:04:03". Then
set format x "%1y/%2m/%3d %01H:%02M:%03S" # "98/ 7/ 6 5:04:003"