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