How can I control what data is uploaded to my GPS?

I have the "Britain's National Parks" disk which contains maps for all these areas. I want to upload just the marks, waypoints and routes for a particular area. However all the data seems to be stored in a single overlay, so when I upload it to the GPS I get it for the whole country, not just the area I'm visiting.

I can create sub-categories for different areas, but as marks, routes, tracks and waypoints are all stored separately I would have to manually move all these into the appropriate category.

Is there a simple way of achieving what I want, so my GPS isn't cluttered with data for Ben Nevis when I'm climbing Snowdon?

HowardJ,

The best way to transfer overlay files onto a GPS device is to right click on the overlay in question and select SEND TO GPS.
This will just transfer the selected overlay.

Thanks

Hi Howard,

Yes, you're correct that Subcategories (or maintaining multiple external overlay files) is the only way to manage large numbers of overlay items and this can take a considerable time as there is no group-select facility in MM (only individual drag and drop).

However, if you have a very large number of Marks or Waypoints in well-separated groups (i.e. which can fit into simple rectangles defined by Latitude and Longitude lines) then you could proceed as follows:

Export all the data as a .CSV file and import into a spreadsheet such as Excel (Open Office is possible but more problematic).

Sort the Latitude column into increasing or decreasing sequence and delete all rows to the north of the rectangle's northern boundary.

Repeat sorting and deleting for the south latitude and east and west longitude limits.

Re-sort to the original order, or alphabetically (particularly to use on PDA version). Save the .CSV file and import back into MM.

You might also be able to use this technique with Routes and Tracks, but it's more complicated because those have header rows (see .CSV in the MM Help : Index pulldown menu).

Tip: When importing or creating large numbers of overlay items, first change the default category names (Track, Route, etc.) to something else (e.g. just add an 's' to the end). Then when you import new data (e.g. GPS tracks recorded over a complete holiday) they will all go into the default category which you can then rename and/or drag into a relevant category.

Cheers, Alan.