请教坛主：
给在中国的妈妈申请移民签证， 今天收到邮件，要先用PDF电邮所有civil documents . 其中一项叫 police certificates .
网上注解是这样的：
If you are 16 years of age or older, you must submit a photocopy of a police certificate from the following locations:
From your... If you were... And resided there...
Country of nationality At least 16 years of age At least 6 months
Country of residence At least 16 years of age At least 6 months
Country of previous residence At least 16 years of age At least 1 year
Any country where you were arrested Any age For any timeframe
Note: Present and former residents of the United States do NOT need to submit any U.S. police certificates.
Important: Police certificates expire after one year, unless the certificate was issued from your country of previous residence and you have not returned there since the police certificate was issued.
请问 这是什么东东？ 到哪申请？
谢谢！