In addition to Common Era (like 2020, 2021, etc.) there are also some year notations widely and frequently used nowadays.
For example, Republic of China calendar (aka. Minguo calendar) and Chinese Lunar Calender are used in Taiwan, and Japanese calendar is used in Japan. In other words, 2021 is the 110th year of the "Republic Era" (aka. Minguo 110th Year = 民國110年); 2021 is the 3rd Year of Reiwa Era in Japan (aka. Reiwa 3rd Year = 令和3年).
I come from Taiwan, where all the government and many companies adopt the "Republic Era" calendar; the situation is the same in Japan.
Therefore, for those who work in government offices or companies as above, it would be highly appreciated if it is possible to choose different calendar eras in dynamic time command.