rdbk_version 1application/x-roadbook.rdbk

The .rdbk standard

One file, the whole roadbook. A .rdbk holds the route, its notes and everything they draw, so any app can open it, follow it and keep it — offline, on any device, years later.

The reference format for digital roadbooks. With no official standard in the field, .rdbk has become the open format that riders, clubs and event organizers around the world know and prefer — for 4×4, motorbike and bike.

Validate a .rdbk See an example

Why .rdbk

• Self-contained. A .rdbk embeds the symbols it uses (as data URIs), so it renders identically anywhere — offline, years later — with no external icon packs to lose.
• Plain JSON inside. Open roadbook.json in any text editor, parse it with one line in any language, diff it in git.
• Map-ready. The full GPS track travels with the notes, so any reader can draw the route and place you on it.
• Symbols are first-class. Each note can carry positioned, rotated, scalable pictograms and colored junction vectors — not just a line of text.

Container (the file)

A .rdbk file is a ZIP container. Inside it, roadbook.json holds the roadbook — the document described below, every symbol it draws and every voice note embedded in it — alongside optional bundled photos:

my-roadbook.rdbk   (ZIP)
├─ roadbook.json     // the roadbook — the document below
├─ media.json        // optional — where each bundled photo was taken
└─ photos/…          // optional — geotagged photos

Photos are optional: they travel only when the exporter includes them. The file's MIME type stays application/x-roadbook.

Document structure

roadbook.json is one JSON object. It holds what the author decided and nothing that can be computed: every distance, bearing and count is derived from the track by whoever reads it, so a file can never contradict itself.

{
  "rdbk_version": 1,       // the version of this standard the file follows
  "meta":  { … },          // the roadbook's details
  "track": [ … ],          // the GPS polyline (ordered points)
  "notes": [ … ],          // the notes, in track order
  "symbols": { … },        // the embedded symbol library (name → data URI)
  "compatibility": { … }   // optional — kept for other formats, one block each
}

Coordinates are WGS-84 decimal degrees with at most 6 decimals. Distances are integer metres. Headings are degrees clockwise from true north (0–359). A value at its default — an empty text, the track road, no rotation — is left out: there is one way to write each thing.

meta

track

An ordered array of at least two points: the route. Notes sit on its points, by index. A point may carry its elevation (integer metres) and its time_ms (the fix time, milliseconds since 1970 UTC), kept from a recording.

"track": [
  { "lat": 45.827120, "lon": 9.411640, "elevation": 1245, "time_ms": 1783065600000 },
  { "lat": 45.827400, "lon": 9.411800 }
]

notes

The heart of a roadbook: at least one note, each on a point of the track, in track order (every track_index greater than the previous one).

{
  "track_index": 184,
  "text": "Bear right onto the gravel track",
  "road_type": 3,
  "cap": 247, "cap_type": "average",
  "speed_limit_kmh": 30,
  "danger": 2,
  "waypoint_type": "masked",
  "symbols": [ { "name": "S03_30km.svg", "position": [40, 22], "size": 32 } ],
  "junctions": [ { "from": [0, 0], "to": [45, 25], "road_type": 4 } ],
  "blocks": [ { "type": "text", "placement": "before", "text": "Deep ford after the bridge — slow down." } ]
}

Derived values

Never written, always computed — the same way by every reader, so two apps show the same numbers. Distances are haversine on a sphere of radius 6 371 000 m, rounded to whole metres.

Symbols (symbols)

A note's symbols places pictograms on a fixed 230 × 162 reference box. The origin is the box centre; +y points up. This makes a note render the same at any display size.

The images live inside the file, in the top-level symbols: a map from name to data: URI. Every name a note uses MUST be there — that is what makes a .rdbk portable. The library may hold more: the author's own symbols, kept for later.

"symbols": {
  "S03_30km.svg": "data:image/svg+xml;base64,PHN2ZyB4bWxucz0i…",
  "P07_ponte.png": "data:image/png;base64,iVBORw0KGgoAAAANS…"
}

Road types

The strokes are the FIA Road Book Lexicon's (Cross Country, 2026). In the vignette every road is 8 units wide; the dash patterns are in the same units.

A note's vignette is a tulip: the road you arrive on enters from the bottom edge to the box centre (its road_type_in), the road you leave on exits from the centre with an arrow at the real turn (its road_type), and the junctions branch from the centre. Where the author drew a road point by point on the track around the note, it follows that shape — derived when drawn, never stored. Colours are the reader's choice; the stroke is the standard.

Junction vectors (junctions)

A note can draw the other roads of its junction: vectors on the same 230 × 162 box, from from to to, each with its road_type (default 2) and the stroke it gives.

"junctions": [
  { "from": [0, 0], "to": [45, 25] },
  { "from": [0, 0], "to": [-30, 40], "road_type": 4 }
]

compatibility

An optional object, at the top level and on a note, with one block per other format, named after it — openrally, gpx. It keeps what that format said and the .rdbk has no field for, so the round trip back loses nothing. A reader that does not know a block ignores it; a writer MUST keep it.

"compatibility": {
  "openrally": [ { "tag": "wpm", "attrs": { "open": "800", "clear": "90" }, "text": "" } ],
  "gpx": { "sym": "Flag, Blue", "osmand_icon": "special_flag_stroke", "osmand_color": "#1010a0" }
}

media.json

Where each bundled photo was taken: { "photos": [ { "file": "photos/…", "lat"?, "lon"? } ] }. Every file is an entry of the container.

Conformance

• A .rdbk is a ZIP container with a UTF-8 roadbook.json inside; extension .rdbk, media type application/x-roadbook.
• A conforming reader MUST refuse a file whose rdbk_version it does not know, compute the derived values as this page defines them and draw each road with its stroke.
• A conforming writer MUST embed every symbol its notes use, MUST NOT write a derived value and SHOULD leave out every value at its default.
• A key a reader does not know is ignored; compatibility blocks are kept on a round trip.
• A conforming reader MUST render a note’s blocks around it — before or after, in order — and MUST NOT number them, place them on the map, score them or emit them as GPX/KMZ waypoints.
• The .rdbk validator checks a file against every rule on this page, in the browser.

Full minimal example

{
  "rdbk_version": 1,
  "meta": { "title": "Demo loop", "author": "Alex Driver", "modified": "2026-09-25", "generator": "RDBK.app" },
  "track": [
    { "lat": 45.8271, "lon": 9.4116 },
    { "lat": 45.829, "lon": 9.4135 },
    { "lat": 45.8305, "lon": 9.415 }
  ],
  "notes": [
    { "track_index": 0, "text": "Start" },
    { "track_index": 2, "text": "Finish",
      "symbols": [ { "name": "I01_arrivo.png", "position": [0, 0], "size": 40 } ] }
  ],
  "symbols": { "I01_arrivo.png": "data:image/png;base64,iVBORw0KGgoAAAANS…" }
}

Frequently asked questions

Open a .rdbk in the Reader Validate a .rdbk