DIGIPIN India: The Future of Digital Addressing

Explore India Post's official DIGIPIN (Digital Postal Index Number) – the revolutionary 10-digit geo-coded address system. Understand its 4x4m grid, benefits, and use our conceptual tools.

Unveiling DIGIPIN: Conceptual Tools & Official System Insights

This platform demystifies grid-based addressing via interactive conceptual tools and offers detailed information on India Post's pioneering official DIGIPIN initiative.

Pinpoint Locational Accuracy

Our illustrative utilities showcase how grid systems achieve remarkable exactitude. India's official DIGIPIN aims for an impressive ~4x4 meter resolution, a significant leap from traditional PINCODEs.

Uniform Digital Identifiers

Discover how unique alphanumeric codes can streamline complex addresses. The official DIGIPIN will be a 10-character, nationally adopted standard for all Indian locations.

Grasping Core Technology

Explore the mechanics behind digital addressing. Learn how India Post's DIGIPIN is engineered as a durable public digital framework to empower citizens and enterprises.

The DigiPin Conceptual Toolkit (For Educational Demonstration)

Interactively explore the workings of grid-based digital addressing. Generate a conceptual DigiPin from an address or coordinates, or find a conceptual location from a DigiPin on the map. Important: These tools are for learning and use a simplified model; they DO NOT produce official India Post DIGIPINs.

Select a point on the map below (uses example coordinates for this demo) to derive its conceptual DigiPin.

A Comprehensive Look at India Post's Official DIGIPIN: Transforming National Addressing

An exhaustive guide to the Digital Postal Index Number (DIGIPIN) – India's forthcoming 10-digit alphanumeric, geo-coded system for precise location identification.

India is embarking on a transformative journey to upgrade its national infrastructure through the Digital Postal Index Number (DIGIPIN). This forward-thinking project, led by India Post (Department of Posts, Ministry of Communications) in a significant partnership with the Indian Institute of Technology Hyderabad (IIT-H), the National Remote Sensing Centre (NRSC), and the Indian Space Research Organisation (ISRO), is set to revolutionize how every location within India's extensive territory is identified, navigated, and managed.

Deciphering the Official DIGIPIN

The official DIGIPIN represents a nationally uniform, geo-referenced digital addressing framework. At its core, it's an advanced grid-based system that allocates a unique, enduring, and highly accurate 10-character alphanumeric identifier to every approximate 4 meter by 4 meter segment across India's entire geographical domain. This encompasses not just the mainland but also its island territories and the vast Exclusive Economic Zone (EEZ) in the adjacent seas.

This initiative extends beyond mere postal code enhancement; it's about establishing a fundamental pillar for effective Geospatial Governance. DIGIPIN aims to drastically simplify location identification, thereby enabling superior efficiency in the delivery of numerous public and private services, markedly improving emergency response capabilities, and fostering unparalleled efficiencies in logistics and supply chain operations.

"DIGIPIN is set to become a strong underpinning for Geospatial Governance, heralding advancements in public service delivery, swifter emergency aid, and heightened logistical competence." - As per Official Communications

The Rationale: Why India Requires DIGIPIN (Evolving from PINCODE)

Shortcomings of the Existing PINCODE Framework

The 6-digit Postal Index Number (PINCODE), introduced with visionary intent on August 15, 1972, has served as the linchpin for mail sorting and delivery in India for over half a century. It categorizes geographical zones under a principal Post Office and its affiliated Branch Post Offices. Though groundbreaking for its era, a single PINCODE frequently spans a considerable expanse – at times entire neighborhoods, multiple hamlets, or several square kilometers. This breadth, adequate for conventional mail, poses notable hurdles in the contemporary digital age.

Meeting the Exigencies of a Digital India

Present-day India is a vibrant, digitally propelled economy. The proliferation of e-commerce, hyperlocal service delivery, smart city initiatives, sophisticated logistics networks, and the urgent necessity for swift emergency aid all demand a far more granular and precise method of addressing. The traditional PINCODE system proves inadequate for these modern requisites:

  • Absence of Pinpoint Accuracy: Inability to precisely identify specific building entrances, individual retail units in a commercial complex, or exact spots within large institutional campuses. This results in delivery uncertainties and operational inefficiencies.
  • Obstacles for Emergency Responders: Challenges in rapidly and accurately pinpointing individuals or incidents, particularly in areas with unnamed streets or high population density.
  • Logistical Inefficiencies: Suboptimal route design and last-mile delivery processes due to imprecise address details, leading to increased expenses and delivery durations.
  • Deficiencies in Integration: Limited direct compatibility with modern GIS (Geographic Information Systems) and sophisticated location-based applications that depend on precise geo-coordinates.

DIGIPIN emerges as India's strategic solution to these challenges, offering a unique, machine-interpretable, and exceptionally accurate digital identity for every distinct, small parcel of land.

The Mechanics of Official DIGIPIN: Fundamental Concept & System Design

The brilliance of DIGIPIN is rooted in its hierarchical, grid-based method of translating geographic coordinates (latitude and longitude) into a compact alphanumeric sequence.

Foundational Tenets:

  • Grid-Centric System: India's entire landmass is overlaid with a sophisticated multi-tier grid.
  • Geo-coordinate Translation: The 10-character DIGIPIN is a direct, algorithmic expression of the latitude and longitude at the center of an ~4x4m cell.
  • Unique & Enduring: Each ~4x4m cell is assigned one distinct DIGIPIN that remains constant, regardless of alterations to physical structures or administrative nomenclature.

The 10-Character Alphanumeric Identifier:

Every DIGIPIN is a 10-character string formulated from a designated set of 16 alphanumeric symbols: 2, 3, 4, 5, 6, 7, 8, 9, C, J, K, L, M, P, F, T. These symbols were meticulously chosen to minimize potential confusion (e.g., avoiding '0' vs 'O', '1' vs 'I') and are employed in the encoding algorithm at each tier of the grid hierarchy.

India's Definitive Bounding Box:

To encompass the entire nation and its maritime jurisdictions, a precise geographical bounding box has been established:

  • Longitude: 63.5 degrees East to 99.5 degrees East
  • Latitude: 2.5 degrees North to 38.5 degrees North

The adopted Coordinate Reference System (CRS) is EPSG:4326 (WGS84), a global standard ensuring system interoperability. This bounding box strategically includes India's mainland, island territories, and the vital Exclusive Economic Zone (EEZ), which extends up to 200 nautical miles from the coastline. This allows for addressing offshore assets, like oil rigs or potential future artificial islands.

Hierarchical Grid Segmentation (10 Tiers):

The creation of a DIGIPIN involves a precise, iterative process of subdividing this master bounding box:

  1. Tier 1 Partitioning: The entire bounding box is initially segmented into a 4x4 grid, yielding 16 large regions. The initial character of the DIGIPIN code signifies which of these 16 Tier-1 regions a given location resides in.
  2. Tier 2 Partitioning: The identified Tier-1 region is subsequently itself subdivided into another 4x4 grid (16 smaller sub-regions). The second character of the DIGIPIN identifies the specific Tier-2 sub-region. Consequently, the first two characters of the code uniquely pinpoint one of 162 = 256 sub-regions within the primary bounding box.
  3. Subsequent Tiers (3 to 10): This systematic subdivision – where the cell from the preceding tier is further divided into a 4x4 grid of 16 smaller cells – persists for an additional 8 tiers. Each succeeding character in the DIGIPIN (from the 3rd to the 10th) refines the location with increasing precision.

Thus, the complete 10-character DIGIPIN uniquely designates one specific cell out of 1610 (over one trillion) potential cells within India's defined bounding box. Each final Tier-10 cell possesses dimensions of approximately 4 meters by 4 meters (this dimension can vary marginally with latitude, being smaller than 3.8m x 4m at the equator, which is well within the accuracy of most commercial GNSS devices).

Grid Cell Labeling Approach:

The allocation of the 16 symbols to the grid cells at each tier adheres to a deliberate strategy:

  • Tier 1 Labeling: The labeling for the initial tier is specially configured so that the Indian mainland is primarily encompassed by the digits 2 through 9. This selection aims for a degree of intuitiveness and ensures that Tier-1 grid lines are strategically positioned to avoid bisecting cities with very large populations. Certain characters from the 16-symbol set (e.g., P, F, T) are utilized for regions beyond the mainland, such as maritime zones, or are held in reserve.
  • Tier 2 to 10 Labeling: For these more granular levels of subdivision (from Tier 2 down to Tier 10), a consistent labeling grid is applied. The 16 symbols are assigned to the 4x4 sub-cells in an anticlockwise, outward-spiraling pattern. This methodology is vital as it imparts inherent directional characteristics and adjacency intelligence into the code's structure. For instance, cells labeled with consecutive symbols (like '6' and '7' at a given tier within a parent cell) are often geographical neighbors. Employing a different grid pattern for Tier 1 versus Tiers 2-10 also serves to prevent unintentional labeling of locations outside India using symbols that might carry special significance at Tier 1.

Illustrative Case: DIGIPIN of Dak Bhawan

Consider Dak Bhawan (the headquarters of India Post), situated at geographical coordinates approximately 28.622788°N, 77.213033°E. Its official 10-character DIGIPIN, for instance, 39J49LL8T4 (official DIGIPINs are continuous, without hyphens), is derived by ascertaining its position at each of the 10 hierarchical grid tiers:

  • The '3' (1st character) is determined by which of the 16 largest Tier-1 grid cells contains Dak Bhawan.
  • The '9' (2nd character) results from subdividing that Tier-1 cell into 16 Tier-2 cells and identifying the specific Tier-2 cell for Dak Bhawan.
  • This meticulous procedure is replicated for all 10 characters, each character refining the location further, until the final ~4x4m grid cell encompassing Dak Bhawan is uniquely identified by the complete 10-character DIGIPIN.

Essential Attributes and Merits of the Official DIGIPIN System

Fundamental Strengths:

  • Unparalleled Precision: Identifies locations to a ~4m x 4m area, enabling genuine doorstep accuracy.
  • Direct Geo-location Correlation: The DIGIPIN is inherently tied to latitude and longitude; approximate geo-coordinates of a cell can be derived from its DIGIPIN with minimal computational effort.
  • Holistic Indian Coverage: Specifically engineered for the Indian milieu, covering all land territory, islands, and crucial maritime regions (EEZ). It can effectively assign unique digital addresses even in extremely densely populated urban settings.
  • User-Considerate Alphanumeric Design: While a 10-character code, efforts have been made to render it as intuitive and manageable as feasible, with some embedded directional cues.
  • Absolute Permanence & Stability: DIGIPINs are founded on fixed geographic coordinates. They are immutable and will NOT alter even if names of states, cities, localities, or roads are modified, or if new buildings are erected or old ones razed. DIGIPIN is conceived as an enduring digital public utility, robust enough to accommodate all future developments.
  • Offline Functionality: The DIGIPIN grid and its logic are designed to operate as an offline addressing reference system. Once the necessary data/algorithm resides on a device, DIGIPINs can be resolved or generated without an active internet link.
  • Public Domain Asset: The DIGIPIN grid system itself is intended to be fully accessible in the public domain, fostering widespread adoption and innovation.
  • Privacy-Conscious Design: Critically, no private or personal address data (like house numbers, resident names, or specific business names within a cell) is stored against the DIGIPIN grid value itself. The DIGIPIN is purely a location reference for a ~4x4m cell, not a repository of its occupants or specific traditional addresses.
  • Scalability and Flexibility: The system is engineered to be scalable for the entire nation and adaptable for integration with existing and future GIS applications and digital services.
  • Optimized Code Length: The 10-character length represents a carefully considered trade-off, designed to be as concise as possible while delivering the requisite high level of addressing precision across India.
  • Independence from Land Use: The DIGIPIN grid is detached from land use patterns or the nature of structures built upon the land.

Groundbreaking Advantages & Extensive Applications of DIGIPIN

The nationwide adoption of DIGIPIN is poised to deliver a wealth of benefits across diverse sectors:

Sector / Domain Key DIGIPIN Benefits and Uses
E-commerce & Logistics Vastly improved final-stage delivery precision, minimized RTOs (Return to Origin), accelerated delivery schedules, optimized routing algorithms, reduced operational expenditures, heightened customer contentment, efficient inventory management.
Emergency Services (Police, Fire, Ambulance) Swifter and more accurate pinpointing of incidents and individuals needing aid, leading to faster response times, potentially safeguarding lives and assets. Essential for both urban and rural contexts.
Public Service Provision Effective and targeted distribution of government initiatives, subsidies, and citizen-focused services. Enhanced address validation for KYC procedures. Improved planning and execution of public infrastructure projects.
Disaster Management & Aid Precise mapping of impacted zones, accurate location of resources and relief distribution points, efficient coordination of rescue and aid efforts during natural disasters like floods, earthquakes, and cyclones.
Healthcare Delivery Enhanced navigation for ambulance services, streamlined delivery of medical provisions, superior tracking for public health campaigns and disease monitoring.
Geospatial Governance & Urban Development Bolsters India’s geospatial data framework, supports the National Geospatial Policy 2022. Facilitates superior urban and rural planning, infrastructure enhancement, land records administration, and property assessment.
Banking & Financial Sector (BFSI) More dependable address verification for customer registration, loan processing, and fraud mitigation. Aids financial inclusion by reaching unbanked/underbanked populations with precise addresses.
Transportation & Navigation Systems Augmented accuracy for GPS navigation tools, fleet operations management, public transit planning, and ride-sharing services.
Agriculture & Rural Advancement Exact location data for soil analysis, crop insurance schemes, targeted subsidy disbursement to farmers, and surveillance of agricultural holdings.
Tourism & Hospitality Industry Simplified identification and navigation to tourist attractions, hotels, and guesthouses, particularly in remote or inadequately addressed locales.
Catalyst for Innovation Functions as a foundational data layer (base stack) for a multitude of novel location-based services (LBS), smart city solutions, IoT deployments, and data analytics.

Evaluating the Official DIGIPIN: Merits and Points to Consider

Principal Advantages (Pros):

  • Extreme Precision & Detail: Unmatched accuracy down to ~4x4 meters, a paradigm shift from broad PINCODE zones.
  • National Uniformity: A single, consistent, and unambiguous digital addressing standard for the entire country.
  • Immutable & Lasting Codes: DIGIPINs are anchored to fixed geo-coordinates, ensuring they remain constant irrespective of changes to man-made features or administrative names.
  • Enhanced Efficiency Across Industries: Optimizes logistics, speeds up emergency response, and refines service delivery for both public and private organizations.
  • Solid Digital Underpinning: Empowers a new wave of location-based services, data analytics, and intelligent governance strategies.
  • Engineered for Offline Operation: The core referencing system can function without continuous internet access, crucial for India's varied terrain and connectivity landscapes.
  • Privacy-Focused Architecture: The DIGIPIN itself is a location identifier for a grid cell, not a storage for personal data associated with that cell.
  • Open Public Framework: The grid system is envisioned as a public resource, nurturing widespread adoption and innovation across diverse platforms.
  • Future-Ready Design: Constructed to be scalable and adaptable to future technological progress and evolving addressing requirements.

Potential Hurdles and Considerations:

  • Broad Adoption and Public Education: Transitioning a nation of over a billion individuals to a new addressing system necessitates comprehensive and sustained public awareness initiatives, outreach programs, and training for diverse stakeholders.
  • Initial Data Integration & Mapping Effort: The task of accurately mapping existing traditional addresses to the new DIGIPIN grid will be a substantial undertaking, demanding sophisticated tools and considerable resources.
  • Technological Infrastructure & Device Precision: While capable of offline use, widespread optimal utility benefits from GNSS-enabled devices for precise coordinate acquisition. The accuracy of consumer-grade GNSS can fluctuate, which might be a factor in some specific scenarios.
  • User Acclimatization and Learning Curve: A 10-character alphanumeric code, though structured, might initially appear more complex to recall or verbally communicate for some population segments compared to the familiar 6-digit PINCODE. User-friendly applications will be pivotal.
  • Vertical Addressing (Multi-Level Structures): DIGIPIN accurately identifies the ~4x4m footprint of a building. For addressing individual units (flats, offices) within multi-story edifices, DIGIPIN will serve as the precise base location, potentially requiring augmentation by existing or new sub-addressing systems (e.g., floor number, apartment identifier).
  • Upkeep of Geospatial Base Information: Ensuring the accuracy and timeliness of the underlying geospatial data and algorithms that define and maintain the DIGIPIN grid will be an ongoing responsibility.
  • Nuances in Rural and Remote Locales: Addressing specific challenges in extremely remote or sparsely inhabited areas, or regions with unique geographical characteristics, will necessitate careful implementation approaches.

Conceptual Insight: How a DIGIPIN Might Be Manually Inferred

While the actual generation and retrieval of official DIGIPINs will be managed by sophisticated software and dedicated applications from India Post, understanding the conceptual foundation of its derivation is enlightening. This is a simplified illustration of the principle and not a practical method for users:

  1. Acquire Precise Geo-Coordinates: The process commences with the highly accurate latitude and longitude of the target point, typically sourced from a dependable GNSS (Global Navigation Satellite System) device or a high-resolution map.
  2. Tier 1 Grid Cell Pinpointing: Utilizing the defined Bounding Box for India (Longitude 63.5-99.5 E, Latitude 2.5-38.5 N), ascertain which of the initial 16 large Tier-1 grid cells (formed by a 4x4 division of the Bounding Box) encloses the target coordinates. The symbol assigned to this specific Tier-1 cell (based on the official Tier-1 labeling scheme) becomes the first character of the DIGIPIN.
  3. Refine Bounding Box for Tier 2: The geographical limits (min/max latitude and longitude) of this identified Tier-1 cell now constitute the new, smaller bounding box for the subsequent step.
  4. Tier 2 Grid Cell Pinpointing: Divide this new, smaller bounding box (the selected Tier-1 cell) into another 4x4 grid, creating 16 Tier-2 sub-cells. Determine which of these 16 sub-cells contains the target coordinates. The symbol assigned to this Tier-2 sub-cell (based on the official Tier 2-10 labeling scheme – e.g., anticlockwise spiral) becomes the second character of the DIGIPIN.
  5. Iterative Refinement (Tiers 3 to 10): Replicate this process for all subsequent 8 tiers. At each tier:
    • The previously identified cell becomes the new bounding box.
    • This bounding box is divided into a 4x4 grid of 16 smaller sub-cells.
    • The sub-cell containing the target coordinates is identified.
    • The symbol for this sub-cell becomes the next character in the DIGIPIN.

Crucial Note on Manual Derivation: Accurately performing this 10-tier hierarchical encoding manually to achieve ~4m precision is exceedingly complex and practically unachievable for a human without advanced computational aids and detailed digital maps of all grid tiers along with the precise symbol assignment rules for each tier. The system is inherently designed for algorithmic computation by software. The explanation above serves merely to illustrate the fundamental encoding principle of progressively narrowing down the location.

Present Status and the Road Ahead for DIGIPIN

Based on publicly available information, India Post, in conjunction with its technical partners (IIT Hyderabad, NRSC, ISRO), has successfully engineered the DIGIPIN system. A beta iteration of DIGIPIN has been launched. This beta phase is instrumental for collecting feedback, comments, and suggestions from various stakeholders. This input will be invaluable for refining the system, addressing potential challenges, and ensuring the final version is robust, intuitive, and caters to the diverse requirements of the nation.

The formal, nationwide deployment of DIGIPIN will be a watershed moment. It signifies a substantial advancement in India's ongoing digital evolution, aiming to create a seamless connection between physical locations and their unambiguous digital representations. DIGIPIN is envisioned not just as an addressing utility but as a core component of India's public digital infrastructure, comparable to foundational platforms like Aadhaar (digital identity) and UPI (digital payments). It is anticipated to foster innovation, augment governance, improve the quality of life for citizens, and provide a significant impetus to the Indian economy.

Keep abreast of official communications from India Post and pertinent government sources for updates on the full-scale implementation and availability of DIGIPIN services.

Developer API (Conceptual Illustration)

Examine how a conceptual DigiPin API could enable integration into diverse applications. (Official API details will be provided by India Post).

Imagining Fluid Integration

This conceptual REST API illustrates how developers might interface with a digital addressing system like DIGIPIN. Core capabilities could encompass converting traditional addresses to DIGIPINs, DIGIPINs back to geo-coordinates, and DIGIPIN validation. Such an API would prove indispensable for:

  • Logistics and e-commerce platforms for optimizing deliveries.
  • Navigation and cartography services.
  • Emergency dispatch and response systems.
  • Government service portals and citizen-centric applications.
Explore Conceptual Tools 
// Example: Convert Address to Conceptual DigiPin
async function getConceptualPin(address) {
  const apiKey = 'YOUR_CONCEPTUAL_API_KEY';
  const apiUrl = 'https://digipin.concept.example/api/v1/to-pin'; // Illustrative API endpoint

  try {
    const response = await fetch(apiUrl, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'X-API-Key': apiKey
      },
      body: JSON.stringify({ queryAddress: address })
    });

    if (!response.ok) {
      throw new Error(`API Error: ${response.status}`);
    }

    const data = await response.json();
    console.log('Conceptual DigiPin:', data.conceptualDigiPin);
    // Example Output: "K9J-4PC-L8F2" (Conceptual)
    return data.conceptualDigiPin;
  } catch (error) {
    console.error('Failed to fetch conceptual DigiPin:', error);
  }
}

getConceptualPin('Gateway of India, Mumbai');

Common Queries Regarding DIGIPIN

Key questions about India's official DIGIPIN framework and this informational resource, addressed.

Is this platform (digipin.web.app) the official India Post DIGIPIN portal?

No. This website (digipin.web.app) serves as an independent, informational project and an interactive guide to the DIGIPIN concept. It is NOT associated with India Post, the Department of Posts, Ministry of Communications, IIT Hyderabad, NRSC, or ISRO. For authoritative information, please consult India Post's official website and government notifications.

How can I use the conceptual toolkit featured here?

Proceed to the Toolkit area. You can:

  1. Input a conventional address to receive a conceptual DigiPin.
  2. Enter latitude/longitude to convert to a conceptual DigiPin.
  3. Type a 10-character conceptual DigiPin to view its approximate map location.
  4. Click the map (using sample coordinates) to obtain a conceptual DigiPin.
Bear in mind, these are for illustrative understanding of grid-based addressing principles only.

What exactly is the official DIGIPIN (Digital Postal Index Number)?

The official DIGIPIN is a significant national undertaking by India Post, in partnership with IIT Hyderabad, NRSC, and ISRO. It's a standardized, countrywide geo-coded addressing system that allocates a unique 10-character alphanumeric identifier to every approximate 4x4 meter plot in India, including its EEZ.

How does the official DIGIPIN markedly differ from the old 6-digit PINCODE?

A PINCODE designates a large geographical zone (e.g., a neighborhood, multiple villages). An official DIGIPIN is extremely specific, identifying a unique ~4x4 meter square. This provides doorstep-level accuracy for deliveries, emergency aid, and numerous other uses, which PINCODEs cannot offer.

Which 16 symbols are employed in the official DIGIPIN code?

The official DIGIPIN system utilizes the following 16 alphanumeric symbols for its encoding: 2, 3, 4, 5, 6, 7, 8, 9, C, J, K, L, M, P, F, T.

What is the precision of an official DIGIPIN address?

The official DIGIPIN system is engineered for an accuracy of roughly 4 meters by 4 meters. This high degree of precision is adequate to identify specific building entrances, small retail outlets, or even distinct points of interest within a larger complex.

Will an official DIGIPIN be altered if buildings are erected or road names are changed?

No. A fundamental characteristic of the official DIGIPIN system is its permanence. DIGIPINs are derived purely from fixed geographic coordinates (latitude and longitude). They are conceived as immutable digital infrastructure and will not be impacted by modifications to physical structures, road networks, or administrative delineations like city or state names.

Does the official DIGIPIN system retain my personal details like name or phone number?

No. The official DIGIPIN system is structured with privacy as a paramount concern. The DIGIPIN code itself is solely a representation of a geographic coordinate (a ~4x4m grid cell). It does not contain or link to any personal information such as names, phone numbers, or specific traditional house address details within that cell. It functions as a location reference, not a personal data archive.

When is the official DIGIPIN system expected to be fully operational for public use?

A beta version of DIGIPIN has been made available by India Post for feedback and enhancement. The schedule for the complete public rollout of official DIGIPIN services and applications will be communicated by India Post through their official channels. This website will strive to share publicly available developments.

How will DIGIPIN benefit commercial entities, particularly in e-commerce and logistics?

DIGIPIN is set to transform e-commerce and logistics by:

  • Furnishing exact drop-off/pickup points, significantly minimizing delivery inaccuracies and RTOs.
  • Facilitating highly efficient route optimization and quicker last-mile deliveries.
  • Reducing operational expenditures and improving overall supply chain transparency.
  • Boosting customer satisfaction through dependable and punctual deliveries.