API Reference > imodeljs-frontend > QuantityFormatting > CustomQuantityTypeDefinition > secondaryPropEditorSpecs secondaryPropEditorSpecs secondaryPropEditorSpecs: undefined | CustomFormatPropEditorSpec[] An array of specifications that are used to generate a label and editor in the UI used to display and edit the FormatProps. UI items defined as secondary will be shown below other UI components that edit FormatProps. Defined in core/frontend/src/quantity-formatting/QuantityFormatter.ts Line 150 Last Updated: 11 June, 2024