anchor.diff:  
   <%= toc %>
   
  -## Provided by Buildkite
  +## Standard Buildkite environment variables
   
  -The following environment variables are automatically provided to every job, and can’t be overriden by your pipeline configuration.
  +The following environment variables are automatically provided to every job, and are read only. They can’t be overriden by your pipeline configuration or environment hooks.
   
   <table>
   <tbody>
  
positive.code: * Pipeline settings — for values that are not secret.
  * [Build pipeline configuration](/docs/pipelines/command-step) — for values that are not secret.
  * An `environment` or `pre-command` [agent hook](/docs/agent/hooks) — for values that are secret or agent-specific.
  
negative.code: </tbody>
  </table>
  
  Bootstrap vars:
  BUILDKITE_DISABLE_GIT_SUBMODULES
  BUILDKITE_REFSPEC
  
  ## How environment variables are interpolated
  
  
  ## Defining your own
  
  You can define environment variables in your jobs in a few ways, depending on the nature of the value being set:
  