anchor.diff:  To create a dedicated coordinating node, set:
   
   [source,yaml]
  --------------------
  +----
   node.roles: [ ]
  --------------------
  +----
  +
  +[[remote-node]]
  +==== Remote-eligible node
  +
  +By default, any node in a cluster can act as a cross-cluster client and connect
  +to <<modules-remote-clusters,remote clusters>>. Once connected, you can search
  +remote clusters using <<modules-cross-cluster-search,{ccs}>>. You can also sync
  +data between clusters using <<xpack-ccr,{ccr}>>.
  +
  +[source,yaml]
  +----
  +node.roles: [ remote_cluster_client ]
  +----
   
   [[ml-node]]
   ==== [xpack]#Machine learning node#
  
positive.code: [[modules-node]]
  === Node
  
  Any time that you start an instance of {es}, you are starting a _node_. A 
  collection of connected nodes is called a <<modules-cluster,cluster>>. If you
  are running a single node of {es}, then you have a cluster of one node.
  
  
negative.code: unexpected data then it will refuse to start. This is to avoid importing
  unwanted <<modules-gateway-dangling-indices,dangling indices>> which can lead
  to a red cluster health. To be more precise, nodes without the `data` role will
  refuse to start if they find any shard data on disk at startup, and nodes
  without both the `master` and `data` roles will refuse to start if they have any
  index metadata on disk at startup.
  
  It is possible to change the roles of a node by adjusting its
  