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#### 14.8.2.23 `:eval`

The `:eval` header argument can be used to limit the evaluation of specific code blocks. The `:eval` header argument can be useful for protecting against the evaluation of dangerous code blocks or to ensure that evaluation will require a query regardless of the value of the `org-confirm-babel-evaluate` variable. The possible values of `:eval` and their effects are shown below.

`never or no`

  The code block will not be evaluated under any circumstances.

`query`

  Evaluation of the code block will require a query.

`never-export or no-export`

  The code block will not be evaluated during export but may still be called interactively.

`query-export`

  Evaluation of the code block during export will require a query.

If this header argument is not set then evaluation is determined by the value of the `org-confirm-babel-evaluate` variable see Code evaluation security.