类名可以包含字母、数字和下划线字符的任何组合，但不能以数字打头。

The class name can contain any combination of letters and Numbers, as well as the underscore character, but cannot begin with a number.

youdao

但是，由于它可以包含字母数字字符，因此它不适于与Sphinx结合使用，Sphinx要求索引的每条记录都有一个惟一的32位整型键。

However, because it can contain alphanumeric characters, it's inappropriate for use with Sphinx, which requires each record indexed to have a unique 32-bit integer key.

youdao

软件包本身的名称(不是文件名，仅仅是软件包的名称)可以包含小写字母、数字以及“-”和“+”字符。

The name of the package itself (not the filename, just the name of the package) can contain lowercase letters, Numbers, and the "-" and "+" characters.

youdao

That's pretty good 'cause now, I can pretty much cover my American keyboard pretty effectively both upper case, lower case, and a whole bunch of punctuation. For other languages as in aside, there are other encoding schemes when there are more characters.

那是相当不错的，它可以包含整个美式键盘中的字符,包括大小写字母和一连串标点,对于其他语言，当涉及更多字符时就会有其他的编码体系。

哈佛公开课 - 计算机科学课程节选