anchor.diff:  ++++
   
   A data stream consists of one or more _backing indices_. Backing indices are
  -<<index-hidden,hidden>>, automatically-generated indices used to store a
  -stream's documents.
  +<<index-hidden,hidden>>, auto-generated indices used to store a stream's
  +documents.
   
   image::images/data-streams/data-streams-diagram.svg[align="center"]
   
  
positive.code: To update or delete specific documents in a data stream, submit one of the
  following requests to the backing index containing the document:
  
  * An <<docs-index_,Index API>> request with an
    <<docs-index-api-op_type,`op_type`>> of `index`.
    These requests must include valid <<optimistic-concurrency-control,`if_seq_no`
    and `if_primary_term`>> arguments.
  
  * A <<docs-bulk,Bulk API>> request using the `delete`, `index`, or `update`
    action. If the action type is `index`, the action must include valid
    <<bulk-optimistic-concurrency-control,`if_seq_no` and `if_primary_term`>>
    arguments.
  
  * A <<docs-delete,Delete API>> request
  
  TIP: If you need to frequently update or delete existing documents across
  multiple indices, we recommend using an <<indices-add-alias,index alias>> and
  
negative.code: sending requests directly to the index. This means you cannot submit the
  following requests directly to any backing index except the write index:
  
  * An <<docs-index_,index API>> request with an
    <<docs-index-api-op_type,`op_type`>> of `create`. The `op_type` parameter
    defaults to `create` when adding new documents.
  * A <<docs-bulk,bulk API>> request using a `create` action
  
  Because it's the only index capable of ingesting new documents, you cannot
  perform operations on a write index that might hinder indexing. These
  