mysql date_format()-在%u和%v标志之间有什么区别?

我在mysql的文档中看到了 date_format() 它返回53或54个不同的值。据我所知,几年有52周或53周。这额外的一周是从哪里来的?

%U  Week where Sunday is the first day of the week (00 to 53)
%u  Week where Monday is the first day of the week (00 to 53)
%V  Week where Sunday is the first day of the week (01 to 53). Used with %X
%v  Week where Monday is the first day of the week (01 to 53). Used with %X

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html

那么U和V标志有什么区别呢?U标志的范围不应该是(00到52)吗?

谢谢!