import type { AssetId } from './asset.js';
/**
 * Normalized, document-scoped anchor id. Frontends that concatenate multiple
 * source parts (EPUB chapters) scope ids during normalization so they stay
 * unique across the whole document.
 */
export type AnchorId = string;
/** Where a link points. */
export type LinkTarget = {
    type: 'external';
    url: string;
} | {
    type: 'relative';
    url: string;
} | {
    type: 'anchor';
    id: AnchorId;
};
export declare function linkTargetIsEmpty(target: LinkTarget): boolean;
/** Where an image's bytes live. */
export type ImageSource = {
    type: 'external';
    url: string;
} | {
    type: 'relative';
    url: string;
} | {
    type: 'asset';
    id: AssetId;
} | {
    type: 'unavailable';
};