X.121地址也称为IDN（国际数据数字，international data number）。X.121地址的长度是不固定的；但是，最大长度被限制为14个十进制数字。
双语例句
1
A growing number of international organizations, countries and regions subject of personal data protection of the rights attention.
越来越多的国际组织、国家与地区对个人资料权的保护给予重视。
2
Oriented to the left vs. right hand motor imagery based BCI, research was carried out for the small number of samples from the public data sets of the 2nd International BCI Algorithm Contests.