/**
 * Represents a single TLV (Tag-Length-Value) structure used in QR codes or similar encoding formats.
 *
 * This entity encapsulates the fundamental components of a TLV:
 * - A tag (identifier)
 * - A value
 * - Its corresponding length (in characters)
 *
 * Optionally, a TLV may contain nested sub-tags (subTags), allowing for hierarchical data structures.
 */
export declare class TlvEntity {
    /** The tag identifier (2-digit or more hexadecimal string). */
    readonly tag: string;
    /** The length of the value in characters. */
    readonly length: number;
    /** The raw value associated with the tag. */
    readonly value: string;
    /** Optional nested TLVs contained within this TLV's value (for composite TLVs). */
    readonly subTags?: TlvEntity[];
    /**
     * Creates a new TLV entity.
     *
     * @param tag - The tag that identifies the data field.
     * @param value - The raw value associated with the tag.
     * @param subTags - (Optional) Nested TLV entities parsed from the value.
     */
    constructor(tag: string, value: string, subTags?: TlvEntity[]);
    /**
     * Serializes the TLV entity back into its string representation.
     *
     * @returns A string in the format: TAG + LENGTH (2 digits) + VALUE.
     */
    toString(): string;
}