arg_name: param
name: $key
type: array|object
description: |
Specifies the field or fields to index and the index order.
For example, the following specifies a descending index on the ``username``
field:
.. code-block:: php
[ 'username' => -1 ]
interface: phpmethod
operation: ~
optional: false
---
source:
file: apiargs-common-param.yaml
ref: $options
...