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[mkgmap-dev] address search problem due to required "State" value

From Steve Hosgood steve at tallyho.bc.nu on Mon Sep 21 17:03:19 BST 2009

Steve Ratcliffe wrote:
> It looks like you can create a file with only the
> sections: 1, 4, 5, 6, 7, 11, 15.
> I shall start off with a header size of 286.
> MDR 1:  A reverse index from maps to the other sections.
> MDR 4:  poi types, partially known
> MDR 5:  Cities
> MDR 6:  unknown, wiki claims it is a list of cities but I don't believe that
I wrote that bit of the wiki, and for me at least it's true. This is 
deduced from an NT map, with a record-length of 3 bytes. I wrote a 
program to grovel the MDR file, comparing MDR5 with MDR6 and it all 
panned out over something like 14000 entries. A bit of a fluke if the 
underlying assumptions weren't true!
> MDR 7:  Street names, optional as may be no streets
> MDR 11: POI's
> MDR 15: Strings
> MDR 1 points to a subsidiary header for each map, there are at least
> 8 subsections in this header, some of which I partially understand
> and I expect that all of them lead back into the other sections.
NT maps (with MDR1 using a record-length of 4 bytes) seems to be listing 
the GMP subtile files. I hear that there are 8 bytes variants - don't 
know about them.

It sounds like a good idea at least to try generating MDR files though - 
go for it!

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