# Command

Optionally, you may specify a command containing an instruction for a machine-to-machine interface so that some actions could be triggered. The command is expected to be a [Rule Language](https://app.gitbook.com/o/mHVsgmp8VieATykD486b/s/kz3AVy8mukfhOsBy0Lvo/~/changes/94/platform-manual/rules/rule-configurator/moost-rule-language) expression.

When a rule's condition matches, then the notification will not only contain a message but the  evaluated expression.

**Example**

<figure><img src="https://2791588365-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fkz3AVy8mukfhOsBy0Lvo%2Fuploads%2FgGZdp7bZ2PurusMjeid7%2Fimage.png?alt=media&#x26;token=d2d7e38a-3c90-4ef8-86b8-c1adc9109b67" alt=""><figcaption></figcaption></figure>

Have a look at [Rule Language](https://app.gitbook.com/o/mHVsgmp8VieATykD486b/s/kz3AVy8mukfhOsBy0Lvo/~/changes/94/platform-manual/rules/rule-configurator/moost-rule-language) to see the full feature set of the expression language.