The year in a date entry is often entered as two digits. Internally, the year is managed by $[officename] as four digits, so that in the calculation of the difference from 01/01/99 to 01/01/01, the result will correctly be two years.
在日期条目中，通常用两个数字表示年份。但 $[officename] 内部使用的是四位数字的年份，因此在计算日期 1/1/99 和 1/1/01 之间相差的年数时，结果是正确的，即两年。