It can be used to refer simply to the name of a method when it's used in a source-code message to an object.

一种是用在代码中向对象发送消息时简单的代表了一个方法名。

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Message information may be authenticated with error-control code, message authenticated code and digital signature.

报文信息的鉴别认证可采用差错控制码、报文鉴别码与数字签名进行。

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The other person receives a text message with a code to take to the local M-Pesa agent to get the money.

VOA: special.2009.11.02

People could send a text message with the code and get a message back confirming that what they bought is listed in a database.

VOA: special.2010.03.01

"they would like to receive a message that uses some kind of code, and instead of sending a message that reminds them of their pill, they would like a motivational message, like for example, 'it's time for your life.'" Services like that have been shown to work in low-income countries, and now they're starting to appear in richer countries.

VOA: standard.2010.02.24

The FBI determined Keyes left behind no code or hidden message in his writings.

WSJ: Alaska killer's writings include disturbing poetry

They send that code, via text message, to a toll-free phone number, and immediately receive a text back that indicates whether or not the drug is legit.

FORBES: Tech Startup Uses Cell Phones To Root Out Counterfeit Drugs

In the prison library, where inmates most ask for Westerns and romance novels, employees scour pages of returned books just to make sure there's not a message or code that could be passed along to another inmate.

CNN: Reporters get first look inside mysterious Supermax prison