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On this page we post our recent findings . It is updated regularly

Garmin devices not showing Chinese/Japanese characters

This has not been reported before, but many new Garmin devices ignore Chinese/Japanese characters embedded in a TYP file

As a result any search for say a 'Chinese restaurant' (中国餐馆) , where the individual name has not been given, results in a blank space and NOT in 中国餐馆.

Unlike Basecamp/Mapsource,these devices do not respond to codepage 932 & 936

Again,unlike Basecamp ,codepage 65001 only works for languages with codepages 1250 -1258

Garmin Geocache ggz files

These are basically a collection of zipped gpx files which can be unzipped using 7+

Each gpx seems to represent a country.

Basecamp won't accept the resulting gpx files and creates an error; however, with some trickery all caches and hints can be displayed.


For some Garmin POIS the subtypes /&10 define the sub category

Example: Car Repairs is set to 0x2F03 , Amusement 0x2d08

Main Category 0x2F03 0x2D08  
sub category 0x2F13 0x2D18  

NT Extended POIs

Currently, nothing is documented about these pois:

In its basic form an extended poi , as with non NT ones, has 6 bytes: type number, subtype number, 2 bytes for longitude and latitude.

The second byte (subtype) is used as follows:

0 1 2 3 4 5 6 7
          has LBL pointers unknown includes label text
          3 bytes variable 3+bytes variable + 3 bytes

 Extra Data bytes
5th bit set
if 5th bit is set then 3 LBL bytes follow long and lat bytes.
6th bit
When 6th bit is set and not 7th bit an extra 3 bytes are added followed by a data stream.; the length of this stream is variable and can contain chunks of the same size + and extra byte. If 7th bit is set then the end has been reached. Chunks are clearly separated and may contain a pointers.

The 3 bytes determine the length of the stream and the structure of its contents, ie 43,33,41 using an understood algo define the stream length as 26 bytes.

As an added complication, extra bytes can be added based on the data that follows these three bytes. ie

82 10 37 can signify a length of 8 or 12 bytes

Various combinations of 3 bytes give the same length,implying that these bytes also provide information about the data stream itself.

7th bit
3 bits are added when 7th bit is set.
Although it mostly contains text , other data can be included as well.
If 7th bit is set and the LBL is not set ,then 2 or 3 bytes are used - ie F1 27 - to provide length & other information about the label.
This does not apply to non NT imgs - where the seventh bit when set follows an entirely different algorithm and all labels are stored in the LBL etc.
This block has a definite length calculated using 2nd (+3rd if even) byte(s) - the algorithm is fully understood.
The first byte seems to be some pointer to its length - if the length <16 (?) we get &f0
The second or 3rd byte (if length >255) signifies the length of the stream - the algorithm is understood.

Extra POIs

All City Navigator and most TOPO maps contain extra pois - TYPWiz displays them separately.
When the 7th bit is set additional bytes are added to refer to the ID found in the TYP file using an algorithm that takes into account properties applying to the POI. Interestingly,many pois refer to Extra POIS not found in a TYP file and can be made visible using IMG2TYP and edited inTYPWiz5 - this is of particular interest with CN TOPO files.
  Created using IMG2TYP

CN TYP files contain additional label information essential for the correct display of the icon.

Example: Poi type number 11017 (bus stop) might refer to & display an extra POI, ie Ski Lift

            type & length label data stream
0e 87 4d 01 ee ff f0 0d B8 1D 00 a8 5a 07

Type 10E07 with label A and length 0d , ie 3

More on extra pois here

For more information on the IMG structure see our 'Exploring IMG Format' pdf


You can set the draw orders of lines in Basecamp by tweaking route types in a lines style file and line bitmaps in a TYP file - see more

JCV File Structure

JCV File structure


This applies to Both Basecamp & Mapsource :

if an element (poi line) has not been given a font color then ,if it has text ,it acquires the current font color ! This means , you can get labels to appear in unexpected colors.- pub names could be red, green blue etc depending on the current fontcolor.

It seems that colours are not set to black when it can't find a fontcolor in the TYP file.

A workaround is to make sure the labels you are concerned about have a font color in the TYP file!

How to turn a line name into capital letters

Basecamp converts words to capital letters with type 0x24

Mapinstall & TYP files

Latest version of Mapinstall - 4.0.4 - has some very useful features.

However, you may find maps selected and so called installed on your gps may not appear;it does not necessarily create gmapsupps if the imgs are not created by Garmin.

Individual TYP files are ignored as it seems to presume that non topo imgs all have the save typ file!

A safer way is to use mkgmap or Gmaptool to combine your IMG & TYP file .

Line 0 x 10200 - 102FF

It seems these are reserved for a particular reason rendering them transparent ,even in Basecamp!

'This route does not match the available maps' error solved

This annoying error can occur when the 'search properties' do not tally with the map.

When you search for a place name on your gps it stores the location name & coordinates in 'recent finds' . This means that if you replace your gmapsupps covering the same region, and click on one of your 'recent finds' it may detect a different map. This is confusing as the map may be the same. What could be different are the mapnumbers or FID. So...

Quick solution : make sure your initial 8 digit mapnumber and FID are ALWAYS the same.

MDX file structure

Mdx files tell Mapsource / Basecamp which img files to use.

Download mdx file format

Garmin POI Bug

When creating a 60x19 POI and 1/3 of the POI from the RIGHT is transparent then the POI cannot be shown - in fact the whole tile cannot be rendered. This applies to truecolor and non truecolor.

If the image is reversed or you place a small dot on the right then it works again!

Disappearing POI RangeI 0x2200 - 0x2300

SInce my software update Feb 2014 these do not get rendered on my oregon 600,despite showing up on Basecamp!

0x7400-0x741f are not rendered on Oregon

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