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NET Subfile
Here we find additional data concerning routable highways ,such as its length , its direction (if one way),the maximum speed allowed, and its house address information if any.
The subfile looks like this:
NET Offset |
NET Header |
00 |
Header Length |
02 |
GARMIN NET |
15 |
Pointer to beginning of NET1 |
19 |
Length of this block |
1D |
Road definitions offset multiplier ( power of 2) |
1E |
NET2 Segmented Roads |
22 |
Length of this block |
26 |
offset multiplier ( power of 2) |
27 |
NET3 Sorted Roads |
2B |
Length of this block |
2F |
Sorted roads record size |
NET1
The following table shows a ‘typical’ road definition entry in NET1 ; the length of each record varies depending on:
- number of labels for each highway up to 4
- number of subdivisions used to render a particular highway
- existence of any address information.
More information and examples in Exploring IMG
Items |
Bytes |
example |
labels |
3 per label |
12 00 00 , 45 00 00, 24 01 81 |
Road Data |
1 |
&44 |
Road Length |
3 |
32 01 = &h132*2 metres |
RGN_index_overview |
1 per record |
1,81 ( ie 2 records) |
Highway pointer |
1 |
01 05 , 01 06 |
Subdivision number |
2 |
|
House_number blocks |
1 |
Set if bit 4 or Road Data is set |
Street Address info block |
varies |
|
NOD length of pointer |
1 |
1 or 2 |
NOD2 offset |
2 or 3 |
See Exploring IMG |