anchor.diff:  // |  +-----------+     +-----------+     +------------+  |
   // +------------------------------------------------------+
   ----
  -
   ====
  
positive.code: * If the query includes <<eql-by-keyword,`by` fields>>, the query uses a
  separate state machine for each unique `by` field value.
  
  .*Example* 
  [%collapsible]
  ====
  A data set contains the following `process` events in ascending chronological
  
negative.code: 
  NOTE: `=` is not supported as an equal operator. Use `==` or `:` instead.
  
  [discrete]
  [[limitations-for-comparisons]]
  === Limitations for comparisons
  
  You cannot chain comparisons. Instead, use a
  <<eql-syntax-logical-operators,logical operator>> between comparisons. For
  example, `foo < bar <= baz` is not supported. However, you can rewrite the
  expression as `foo < bar and bar <= baz`, which is supported.
  
  You also cannot compare a field to another field, even if the fields are changed
  using a <<eql-functions,function>>.
  
  *Example* +
  The following EQL query compares the `process.parent_name` field
  