The major change is the replacemeat of pure numerical form of code structure by alphabet - numerical one.

它的主要变化是将编码结构由原来的纯数字式改为字母-数字式。

youdao

The major change is the replacemeat of pure numerical form of code structure by alphabet - numerical one.

它的主要变化是将编码结构由原来的纯数字式改为字母-数字式。

youdao