Service.pid (Constants.SERVICE_PID) - a string, or array of strings, representing the service's persistent identifier.

pid (Constants . SERVICE_PID) -字符串，代表服务的pid (persistent identifier)。

youdao

A deputy object has its own persistent identifier, and may have additional attributes and methods that are not derived from its source objects.

一个代理对象享有其自己的标识符，而且除了继承源对象的属性和方法外，还能拥有独自的属性和方法。

youdao

Set if the column contains a persistent row identifier that cannot be written to, and has no meaningful value except to identify the row.

如果列包含无法向其写入的持久性行标识符，并且除了标识行外没有其他有意义的值，则应设置该值。

youdao

However, no parental notice and consent is required when an operator collects a persistent identifier for the sole purpose of supporting the website or online service's internal operations, such as contextual advertising, frequency capping, legal compliance, site analysis, and network communications.

ENGADGET: FTC introduces changes to Children's Online Privacy Protection Act, parental permission now required to collect information