diff --git a/Adding-a-new-operation.md b/Adding-a-new-operation.md
index ef82b5b..b89bfd8 100644
--- a/Adding-a-new-operation.md
+++ b/Adding-a-new-operation.md
@@ -50,11 +50,13 @@ Operation arguments (ingredients) can be set to any of the following types:
      - User is presented with a checkbox, operation receives `true` or `false`.
  7. `option`
      - Given an array of strings, the user is presented with a dropdown selection box with each of those strings as an option. The selected string is sent to the operation.
+     - You can use the `defaultIndex` property to define which index should be selected by default, if required.
  7. `populateOption`
      - Given an array of `{name: "", value: ""}` objects, the user is presented with a dropdown selection box with the names as options. The corresponding value will be assigned to whichever argument index the `target` parameter is set to.
      - See the *Regular expression* configuration in `src/core/config/OperationConfig.js` for an example of how this works.
  8. `editableOption`
      - Given an array of `{name: "", value: ""}` objects, the user is presented with an editable dropdown menu. The items in the dropdown are labelled with `name` and set the argument to `value` when selected.
+     - You can use the `defaultIndex` property to define which index should be selected by default, if required.
  9. `toggleString`
      - User is presented with a string input box with a toggleable dropdown attached.
      - Populate the dropdown using the `toggleValues` property.