OV2 files are binary files containing variable-length records. Information in an OV2 file is either Integer (signed, little-endian) or String (null terminated). Longitudes and latitudes are stored as integers representing the decimal lon/lat value multiplied by 100000, so 118.5 degrees West longitude is stored as -11850000.
The first byte of each record is the Record Type:
0: Deleted POI Record
1: Skipper Record
2: Regular POI Record
3: Extended POI Record
For POI records (types 0, 2, and 3), the following 4 bytes contain the Record Length, which is the length of the entire record (including the byte for the Record Type and the 4 bytes for the Record Length). The next 4 bytes contain the Longitude, and the 4 bytes after that contain the Latitude. The remaining bytes represent null-terminated string values (the name of the POI, plus some other string values for Extended POI records).
| Record Byte(s) | Contents |
|---|---|
| 0 | Record Type (0, 2, or 3) |
| 1 through 4 | Record Length |
| 5 through 8 | Longitude |
| 9 through 12 | Latitude |
| 13 through (Record Length - 1) | Null-terminated string value(s) |
Skipper records (type 1) are always 21 bytes long. They contain two sets of lon/lat pairs for the North-East and South-West corners of a rectangle, along with a "Block Length". For a given location (say, the current position of the vehicle), if that location falls outside the rectangle then we can just skip the next n bytes of the file.
| Record Byte(s) | Contents |
|---|---|
| 0 | Record Type (1) |
| 1 through 4 | Block Length (bytes to skip) |
| 5 through 8 | Longitude of NE corner |
| 9 through 12 | Latitude of NE corner |
| 13 through 16 | Longitude of SW corner |
| 17 through 20 | Latitude of SW corner |
For an example of how the TomTom device can use these Skipper Records, see How Indexing Helps.