nsub!(/(?:(?:#{DAY_OF_WEEK_NB}\s+(?:and\s+)?){1,7})?#{MONTH_OF_YEAR}\s+(?:the\s+)?((?:#{DATE_DD_WITHOUT_SUFFIX_NB}\s+(?:and\s+)?(?:the\s+)?){1,31})/) do |m1, m2|
        month_str = (ZDate.months_of_year.index(m1) + 1).to_s
        m2.gsub(/(and|the)/, '').gsub(/#{DATE_DD_NB_ON_SUFFIX}/) { month_str + '/' + Regexp.last_match(1) }  # last match is from nested match