anchor.diff:  When the domain line is omitted, `cf` assigns your application to the default domain. Use the domain line when you want your application to be served from a domain other than the default.
   
   ~~~
  -domain: ${target-base}
  +domain: unique9876.example.com
   ~~~
   
   ### <a id='env-block'></a>Environment variables ###
   
  -The `env` block consists of a heading, then one or more environment variable/value pairs. The variables belong to the environment of the container to which the application is deployed on the server.
  +The `env` block consists of a heading, then one or more environment variable/value pairs. An application is deployed to a container on the server. The variables belong to the environment of the container.
   
   For example:
   
  
positive.code: memory: 256M
  instances: 1
  services:
   singular-mysql:
    label: mysql
    provider: mysql
    version: n/a
    plan: dev-sandbox
  
  # app-specific configuration
  applications:
   - name: springtock
     host: springtock333
     path: ./spring-music/build/libs/spring-music.war
   - name: petclinic
     subdomain: petclinic-${random-word}
     path: ./grails-petclinic/target/pets4u-0.1.war
  ~~~
  
  **simple-prod-manifest.yml**
  
negative.code:   RACK_ENV: ${rails-env}
  ~~~
  
  While the application is running, `cf` allows you to operate on environment variables.
  
  * View all variables:
  
   `cf env <app>`
  * Set an individual variable:
  
   `cf set-env <variable_name> <variable_value>`
  * Unset an individual variable:
  
   `cf unset-env <variable_name> <variable_value>`
  
  Environment variables interact with manifests by somewhat complicated rules:
  
  