He wondered whether they should be ditched altogether in favour of an alphanumeric system.

他在考虑是否应该完全放弃方块字，转而采用字母数字系统。

Zip codes are made from digits, unlike the alphanumeric Canadian system, which can encode more information per character.

邮政编码由数字组成， 这与加拿大的字母数字系统不同，后者可以为每个字符编码更多信息。