The field editor cascade is a cascade used to choose a template for rendering the field editor within the EditTemplate.

The default field editor cascade only contains one element:

1. Use the tiddler $:/core/ui/EditTemplate/fieldEditor/default to render the field

See Customizing EditTemplate field rendering for more details.

You can see the current settings for the field editor cascade in $:/ControlPanel under the Info -> Advanced -> Cascades -> Field Editor tab.