%u The day of the week as a decimal, range 1 to 7, Monday being 1. See also %w. (SU)
%U The week number of the current year as a decimal number, range 00 to 53, starting with the first Sunday as the first day of week 01. See also
%V and %W.
%V The ISO 8601 week number (see NOTES) of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least
4 days in the new year. See also %U and %W. (SU)
%w The day of the week as a decimal, range 0 to 6, Sunday being 0. See also %u.
%W The week number of the current year as a decimal number, range 00 to 53, starting with the first Monday as the first day of week 01.