import { _PdfObjectIdentifier } from './identifier-mapping';
/**
 * Represents an internal structure used to describe external PDF data,
 * including object references, descriptors, and encoded content.
 *
 * @private
 */
export declare class _PdfExternal {
    /**
     * Represents the internal direct object reference associated with the external value.
     *
     * @private
     */
    _directReference: _PdfObjectIdentifier;
    /**
     * Represents the internal indirect reference number linked to the external value.
     *
     * @private
     */
    _indirectReference: number;
    /**
     * Represents the internal data value descriptor that describes the nature of the external content.
     *
     * @private
     */
    _dataValueDescriptor: string;
    /**
     * Represents the internal encoding of the external data, which may include byte arrays,
     * bit strings, or single ASN.1 type encodings.
     *
     * @private
     */
    _encoding: any;
    constructor(directReference: _PdfObjectIdentifier, indirectReference: number, dataValueDescriptor: string, encoding: any);
    /**
     * Converts the internal external value into a human readable string representation.
     *
     * @private
     * @returns {string} A formatted textual representation of the external data value.
     */
    _toString(): string;
    /**
     * Converts the internal external value into a JSON compatible representation.
     *
     * @private
     * @returns {any} A JSON object containing the external value s references, descriptor,
     * and encoded data.
     */
    _toJson(): any;
}