anchor.diff:  }
   --------------------------------------------------
   <1> By using `_count` instead of a metric name, we can calculate the moving average of document counts in the histogram
  +
  +[[dots-in-agg-names]]
  +[float]
  +=== Dealing with dots in agg names
  +
  +An alternate syntax is supported to cope with aggregations or metrics which
  +have dots in the name, such as the ++99.9++th
  +<<search-aggregations-metrics-percentile-aggregation,percentile>>. This metric
  +may be referred to as:
  +
  +[source,js]
  +---------------
  +"buckets_path": "my_percentile[99.9]"
  +---------------
   
   [[gap-policy]]
   [float]
  
positive.code: `sales_per_month` date histogram.
  
  [float]
  ==== Special Paths
  
  Instead of pathing to a metric, `buckets_path` can use a special `"_count"` path.  This instructs
  the pipeline aggregation to use the document count as it's input.  For example, a moving average can be calculated on the document
  
negative.code: allowing pipeline aggregations to be chained.  For example, you can chain together two derivatives to calculate the second derivative
  (i.e. a derivative of a derivative).
  
  NOTE: Because pipeline aggregations only add to the output, when chaining pipeline aggregations the output of each pipeline aggregation
  will be included in the final output.
  
  [[buckets-path-syntax]]
  