/**
 * OPC relationships parts (`.rels`) parse / serialize / resolve.
 *
 * XSD: `specs/ecma/.../OpenPackagingConventions-XMLSchema/opc-relationships.xsd`
 * Namespace: `http://schemas.openxmlformats.org/package/2006/relationships`
 *
 * External targets (`TargetMode="External"`) are never fetched.
 *
 * @private
 */
/**
 * One OPC relationship.
 */
export interface OpcRelationship {
    readonly id: string;
    readonly type: string;
    /** Raw Target attribute as stored. */
    readonly target: string;
    readonly targetMode?: 'Internal' | 'External';
    /**
     * Resolved absolute part name for Internal targets; raw URI for External.
     */
    readonly resolvedTarget: string;
}
/**
 * Parse a relationships part.
 *
 * @param bytes - `.rels` payload
 * @param sourcePart - source part absolute name, or `null` for package-level
 * @param partName - OPC name of this relationships part (for errors)
 */
export declare function parseRelationships(bytes: Uint8Array, sourcePart: string | null, partName: string): OpcRelationship[];
/**
 * Serialize relationships to XML bytes.
 */
export declare function serializeRelationships(relationships: ReadonlyArray<OpcRelationship>): Uint8Array;
/**
 * Map key for package-level relationships collections.
 */
export declare const PACKAGE_RELATIONSHIP_SOURCE: null;
export declare type RelationshipSourceKey = string | typeof PACKAGE_RELATIONSHIP_SOURCE;
/**
 * Build the ZIP/OPC part name for a relationship collection key.
 */
export declare function relationshipPartName(source: RelationshipSourceKey): string;