[mkgmap-dev] MDR success and a couple of questions

Wed Sep 23 10:04:42 BST 2009

Steve Ratcliffe wrote:
> On 22/09/09 16:31, Steve Hosgood wrote:
>   
>> On my NT map, MDR9 only contains a single 4-byte element, containing
>> just 01 01 00 00 just as you describe. So evidently that's an accepted
>>     
>
> OK Thanks, that is encouraging.  I shall just plough on, hoping that
> is all we need in 9 for now.
>
>   

This would seem to agree with the current comments on the wiki about 
MDR9 - that the contents (in this case) would be a set of records in the 
form <single byte integer><three byte integer>, and in this case both of 
the integers are '1'. This would agree with evidence elsewhere that 
seems to show Garmin's indexing usually starts from one.

I'll issue a wild guess here that MDR9 is a sort-of "chapter list" for 
MDR10/11, splitting the POI list into a number of categories.

Steve - next time you're playing in this area, could you try putting in 
about 10 POIs into MDR10/11 and adding a second record to MDR9 with the 
value 0x02, 0x04, 0x00, 0x00 please? Then look to see if the POI search 
facility has somehow split into two sections. I'd expect 3 items in one 
section and 7 in the other if there were 10 items total.

It could be that the <three byte integer> is an absolute byte offset, 
not an index into the POI list, but I consider this rather unlikely.

Steve

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