anchor.diff:  
   ##<a id='contract'></a> Core Buildpack Communication Contract
   
  -This section describes the communication contract followed by the Cloud Foundry core buildpacks. This contract enables buildpacks to interact with one another, so that developers can use multiple buildpacks with their applications.
  +This section describes the communication contract followed by the <%= vars.app_runtime %> core buildpacks. This contract enables buildpacks to interact with one another, so that developers can use multiple buildpacks with their applications.
   
   Buildpack developers must ensure their custom buildpacks follow the contract.
   
  
positive.code: 
  To specify a default version:
  
  1. Add the `default_version` object to your manifest, following the [rules](#rules) below. You can find a complete example manifest in the Cloud Foundry [go-buildpack](https://github.com/cloudfoundry/go-buildpack/blob/f1a380f2f3a8012491c6007948af74676713dd50/manifest.yml) repository. 
  
  1. Run the `default_version_for` script from the [compile-extensions](https://github.com/cloudfoundry/compile-extensions) repository, passing the path of your `manifest.yml` and the dependency name as arguments. The following command uses the example manifest from step 1:
    <pre class="terminal">
  
negative.code: 
  <strong><%= modified_date %></strong>
  
  This topic describes how to create custom buildpacks for <%= vars.app_runtime_first %>.
  
  For more information about how buildpacks work, see the [Understanding Buildpacks](understand-buildpacks.html) topic.
  
  ## <a id='packaging-custom-buildpacks'></a> Package Custom Buildpacks ##
  
  <%= vars.app_runtime %> buildpacks can work with limited or no Internet connectivity. The [Buildpack Packager](https://github.com/cloudfoundry-incubator/buildpack-packager) RubyGem gives the same flexibility to custom buildpacks, enabling them to work in partially or completely disconnected environments.
  
  ### <a id='use-buildpack-packager'></a> Use the Buildpack Packager
  
  