# BookmarkFormValidatorCallback

typedef

[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-bookmark/src/ui/bookmarkformview.ts#L318)

#### Parameters

* `form: BookmarkFormView`

#### Returns

* `string | undefined`

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Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)