Variables begin with a percent symbol (%) and stand in for information that can't be known when the configuration file was written. 在编写配置文件时,变量都以百分比符号(%)开始,表示未知的信息。
They use the percent (%) symbol instead of the ampersand, and can be either named entities or external entities. 它们使用百分号(%)而不是与字符,可以是命名实体或外部实体。