anchor.diff:  = Configuration specification
   :toc: left
  +:toclevels: 5
   
   This page specifies the configurations available in Envelope.
   
  
positive.code: |append.raw.value.field.name
  |The name of the appended field that contains the raw input value. Default `_value`.
  
  ||
  |`_morphline_`|
  
  |encoding.key
  |The character set of the incoming key and is stored in the Record field, `_attachment_key_charset`. This must match the encoding of the Envelope input. The key value is stored in the field, `_attachment_key`.
  
negative.code: |field.names
  |The name of the fields used to match between the two datasets. The field names must be identical in name and type. A row is excluded if all of the fields are equal between the datasets.
  
  |===
  
  ==== Select
  
  Deriver `type` = `select`.
  
  [cols="2,8", options="header"]
  |===
  |Configuration suffix|Description
  
  |step
  |The name of the dependency step from which to select columns as output of the current step.
  