anchor.diff:  In this case, the `*sourceStrategy*` definition is consuming the `latest` tag of
   the image stream named `ruby-20-centos7` located within this namespace.
   
  -. Define an image change trigger:
  -+
  -====
  -
  -----
  -{
  -  "type": "imageChange",
  +. Define a build with one or more triggers that point to image streams:
  ++
  +====
  +
  +----
  +{
  +  "type": "imageChange", <1>
     "imageChange": {}
   }
  -----
  -====
  -+
  -This defines an image change trigger that monitors the `*ImageStream*` and
  -`*Tag*` as defined by the strategy's `*from*` field. When a change occurs, a new
  -build is triggered and is supplied with an immutable Docker tag that points to
  -the new image that was just created. This new image will be used by the strategy
  -when it executes for the build. For example, the resulting build will be:
  -+
  +{
  +  "type": "imagechange", <2>
  +  "imageChange": {
  +     "from": {
  +       "kind": "ImageStreamTag",
  +       "name": "custom-image:latest"
  +     }
  +  }
  +}
  +----
  +
  +<1> An image change trigger that monitors the `*ImageStream*` and
  +`*Tag*` as defined by the build strategy's `*from*` field. The `*imageChange*` part
  +must be empty.
  +<2> An image change trigger that monitors an arbitrary image stream. The `*imageChange*`
  +part in this case must include a `*from*` field that references the `*ImageStreamTag*` to monitor.
  +====
  +
  +When using an image change trigger for the strategy image stream, the generated build
  +is supplied with an immutable Docker tag that points to the latest image corresponding
  +to that tag. This new image reference will be used by the strategy
  +when it executes for the build. For other image change triggers that do not
  +reference the strategy image stream, a new build will be started, but the build
  +strategy will not be updated with a unique image reference.
  +
  +In the example above that has an image change trigger for the strategy, the resulting build will be:
  +
   ====
   
   ----
  
positive.code: `_<system-registry>_` is defined as a service with the name `docker-registry`
  running in OpenShift.
  
  . Define a build with a strategy that consumes the image stream:
  +
  ====
  
  
negative.code: the build that is created uses the `*immutableid*` resolved from the
  `*ImageStream*` referenced by the `*Strategy*`. This ensures that builds
  are performed using consistent image tags for ease of reproduction.
  
  [NOTE]
  ====
  Image streams that point to Docker images in v1 Docker registries will only trigger a build
  once when the image stream tag becomes available and not on subsequent image updates. This is due
  to the lack of uniquely identifiable images in v1 Docker registries.
  ====
  
  [#using-docker-credentials-for-pushing-and-pulling-images]
  == Using Docker Credentials for Pushing and Pulling Images
  