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File Format Documentation

I have fun reverse engineering file formats and creating a documentation. Here are some results of my work.

The documentation comes as a PDF (portable document format) file which describes the sections and fields that make up the file together with their purpose. It also contains a reference section which contains links to the used sources of information, to programs using this file format, and to places where sample files can be obtained.

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Garmin

firmware file Firmware File

Filename extensions: *.BIN
Single ARM firmware file for Garmin outdoor GPS devices.This type of firmware files is encountered only embedded in GCD and RGN firmware update files.
Last change: 2019-03-02
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firmware file Firmware Update

Filename extensions: *.GCD
Firmware update file for Garmin outdoor GPS devices.
Last change: 2019-03-02
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container Image and UserData Container

Filename extensions: *.IMG and *.ADM
Garmin Image (IMG) and UserData (ADM) Container File Format.
This file format is used to combine a set of files into a single file. It is similar to a file system on a disk, but it lacks hierarchy. The contained files (called subfiles) form a flat list - there are no subdirectories.
This file format is used for image files (IMG) with filename extension *.img and for user data files (ADM) with filename extension *.adm.
There are separate documents available here for the IMG and ADM subfiles.
Last change: 2019-11-17
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map Map

Filename extensions: *.DEM, *.GMP, *.IDX, ...
Garmin IMG map file for use in outdoor GPS devices.
Uses the IMG/ADM container file format (documentation also available here) to combine all the subfiles into a single file.
This document describes the file format of the following subfile types:
Last change: 2019-11-16
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user data UserData

Filename extensions: *.PRX, *.RTE, *.TRK and *.WPT
Garmin ADM file for storage of user data on marine GPS devices.
Uses the IMG/ADM container file format (documentation also available here) to combine all the subfiles into a single file.
This document describes the file format of the following subfile types:
Last change: 2018-11-17
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index Map Index

Filename extensions: *.MDX
Garmin map index file for use with MapSource and BaseCamp.
Last change: 2019-05-05
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mapsource MapSource / BaseCamp

Filename extensions: *.MPS, *.GDB and *.GFI
Files with filename extension *.mps are created by MapSource. Starting with version 6, MapSource introduced a slightly modified format using filename extension *.gdb. BaseCamp stores its user interface data in *.gfi format.
Last change: 2018-01-01
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firmware file Firmware Update

Filename extensions: *.RGN
Firmware update file for Garmin outdoor GPS devices.
RGN probably stands for "region". Note that the RGN files contained in IMG files have a completely different structure and purpose.
Last change: 2019-02-26
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topographic database Topographic Database

Filename extensions: *.TDB
Topographic Database: The file that holds the information which *.img belong to the mapset. Mapset: An assortment of map tiles (*.img) that is joined together by .tdb, overview image (mapset00.img), and .mdx (cited from here).
Last change: 2019-03-08
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Navico (Lowrance, Simrad, B&G)

map Atlas Type 5

Filename extensions: *.LCM and *.AT5
Navico map format.
The AT5 map format is a Lowrance map format supported by a wide range of Lowrance GPS devices [..]. The AT5 format is able to combine vector layers, such as contour lines, with raster (image) layers (cited from here).
AT5-charts work with seachart-plotters from Lowrance, Simrad and B&G. It is also possible to use them with Insight Planner which is a tool for marine navigation (cited from here).
Last change: 2018-01-01
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map creator Map Creator Project

Filename extensions: *.SAP
Navico Map Creator / Insight Map Creator Project File. Stores all program settings and the directories and file names of input and output files.
Last change: 2018-01-01
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sonar Sonar Log

Filename extensions: *.SLG, *.SL2 and *.SL3
Binary format used by Navico chart plotters to save tracks. *.slg is format 1 (sonar only), *.sl2 is format 2 ( sonar and structure) and *.sl3 is format 3 (includes ForwardScan).
Last change: 2018-01-01
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help Information File

Filename extensions: *.NIF
A Navico Information File (NIF) is created when you use menu entry Settings > System > About > Create report. The report is a comprehensive picture of everything connected to your system, its configuration, status and settings (cited from here).
This file is just an archive in the "tar" format which is then compressed with gzip. To open the file and extract its contents on a Windows operating system, you can use the command line tools tar and gzip from the Cygwin project, or you can use archivers like 7-Zip (use context menu entry 7-Zip > Open in Windows Explorer) or WinRAR (rename *.nif to *.tar.gz first).

Other

Panasonic (Matsushita, Technics, JVC)

firmware file HD Writer AE

Filename extensions: *.CONT, *.IIS, *.TMB and *.PMPD
HD Writer AE is a program from Panasonic that comes with their Digital Video Cameras which use the AVCHD recording format.
A *.cont file describes the content of a scene or directory, an *.iis file contains data for the Intelligent Index System, an *.mtv file contains additional info for the MPEG2 video (*.m2ts), a *.tmb contains a thumbnail image, and an *.pmpd file contains "maker private data".
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The icons on this page were taken from:
  camera_128.png is from pack "Stock" by Leonid Wozniuk, license is CC BY-NC-ND 3.0
  compfile.png and wifi.png are from pack "Dark Glass" by Alessandro Rei, license is GNU GPL
  container.png is a cut-out of moritz-kindler-w2pBTamLhhg-unsplash.jpg by Moritz Kindler on Unsplash
  content.png is from pack "RM Kute Toolbar Icons" by Teekatas S., license is CC BY-NC-ND 3.0
  Crystal_Clear_app_database.png, Crystal_Project_kfloppy.png and Crystal_Project_starthere.png are by Everaldo Coelho (YellowIcon), license is LGPL.
  dossierbleu_documents.png is from pack "Crystal like" by Tidav.
  layers.png is from pack "GIS/GPS/MAP" by Icons-Land, license is Icons-Land Demo License Agreement

Author: Herbert Oppmann (email adress) updated: 2019-11-17