个人认为也可以是平级。我实习的地方给合作方发邮件请求某某文件或者图片和信息, 标题都用" a request for XXX"
the act of politely or officially asking for something:
They received hundreds of requests for more information.[ + to infinitive ] The boss refused our request to leave work early.The clause was added to the contract at Carlos's request (= because Carlos asked for this).An application form will be sent to you on request (= if you ask).
