anchor.diff:  
   ### <a id='CF-INSTANCE-PORT'></a>CF\_INSTANCE\_PORT ###
   
  -The external (host-side) port corresponding to the internal (container-side) 
  -port with value [PORT](#PORT). 
  -For instances on Diego, this value is generally different from the 
  +The external (host-side) port corresponding to the internal (container-side)
  +port with value [PORT](#PORT).
  +For instances on Diego, this value is generally different from the
   [PORT](#PORT) of the app instance.
   
   `CF_INSTANCE_PORT=61045`
   
   ### <a id='CF-INSTANCE-PORTS'></a>CF\_INSTANCE\_PORTS ###
   
  -The list of mappings between internal (container-side) and external (host-side) 
  +The list of mappings between internal (container-side) and external (host-side)
   ports allocated to the instance's container.
  -Not all of the internal ports are necessarily available for the application to 
  -bind to, as some of them may be used by system-provided services that also run 
  +Not all of the internal ports are necessarily available for the application to
  +bind to, as some of them may be used by system-provided services that also run
   inside the container.
  -On the DEAs, these internal and external values are the same, but on Diego 
  +On the DEAs, these internal and external values are the same, but on Diego
   Cells they may differ.
   
   `CF_INSTANCE_PORTS=[{external:61045,internal:5678},{external:61046,internal:2222}]`
  +
  +### <a id='DATABASE-URL'></a>DATABASE\_URL ###
  +
  +At runtime, Cloud Foundry creates a `DATABASE_URL` environment variable
  +for every application based on the [VCAP_SERVICES](#VCAP-SERVICES) environment variable.
  +
  +Cloud Foundry uses the structure of the `VCAP_SERVICES` environment
  +variable to populate `DATABASE_URL`.
  +Any service containing a JSON object with the following form will be recognized
  +by Cloud Foundry as a candidate for `DATABASE_URL`:
  +
  +    {
  +      "some-service": [
  +        {
  +          "credentials": {
  +            "uri": "<some database URL>"
  +          }
  +        }
  +      ]
  +    }
  +
  +Cloud Foundry uses the first candidate found to populate `DATABASE_URL`.
  +
  +Example VCAP_SERVICES:
  +
  +    VCAP_SERVICES =
  +    {
  +      "elephantsql": [
  +        {
  +          "name": "elephantsql-c6c60",
  +          "label": "elephantsql",
  +          "credentials": {
  +            "uri": "postgres://exampleuser:examplepass@babar.elephantsql.com:5432/exampledb"
  +          }
  +        }
  +      ]
  +    }
  +
  +Based on this `VCAP_SERVICES`, Cloud Foundry creates the following
  +`DATABASE_URL` environment variable:
  +
  +    DATABASE_URL = postgres://exampleuser:examplepass@babar.elephantsql.com:5432/exampledb
   
   ### <a id='HOME'></a>HOME ###
   Root folder for the deployed application.
  
positive.code: 
  ## <a id='app-system-env'></a>Application-Specific System Variables ##
  
  The subsections that follow describe the environment variables that Cloud 
  Foundry makes available to your application container.
  Some of these variables are the same across instances of a single application, 
  and some vary from instance to instance.
  
  You can access environment variables programmatically, including variables 
  defined by the buildpack.
  For more inforation, refer to the buildpack documentation for 
  [Java](../../buildpacks/java/java-tips.html#env-var), 
  [Node.js](../../buildpacks/node/node-tips.html#env-var), and 
  [Ruby](../../buildpacks/ruby/ruby-tips.html#env-var).
  
  ### <a id='CF-INSTANCE-ADDR'></a>CF\_INSTANCE\_ADDR ###
  The [CF\_INSTANCE\_IP](#CF-INSTANCE-IP) and 
  [CF\_INSTANCE\_PORT](#CF-INSTANCE-PORT) of the app instance in the format 
  `IP:PORT`.
  
  `CF_INSTANCE_ADDR=1.2.3.4:5678`
  
negative.code: 
  ### <a id='VCAP-APP-HOST'></a>VCAP\_APP\_HOST
  
  The IP address of the host. Deprecated: the DEAs set this to be `0.0.0.0`, and
  Diego Cells do not provide this environment variable.
  
  `VCAP_APP_HOST=0.0.0.0`
  