This is the official manual for the latest Org-mode release.
:eval header argument can limit evaluation of specific code
blocks. It is useful for protection against evaluating untrusted ‘src’
code blocks by prompting for a confirmation. This protection is independent
never or no
never-export or no-export
:eval header argument is not set for a source block, then Org
determines whether to evaluate from the
variable (see Code evaluation security).