正文一律用小写字体。

The text is all in lower case.

让我们输入一些小写的东西。

Let's actually type in something in all lowercase.

也有可能看见在语言和国家代码之间使用连字元，或者把国家代码写成小写形式的变体。

You might also see variations that use a hyphen between the language and country code, or that put the country code is in lowercase.