Subject: PNT file format From: Paul B. Anderson (804) 853-7595 E-mail: pbander@infi.net The PNT format was devised by Fred Popeschil and Antonio Rivera for their public domain Micro World Data Bank II (MWDBII) data base. The PNT file is a binary file where each full record consists of 3 short integer values. Possible 1st short Integer value: Header Values Feature ------------- ------- 1 Data Level 2 Data Level 3 Data Level 4 Data Level 5 Data Level 1000 -> 1999 coastlines 2000 -> 2999 country 4000 -> 4999 internal political borders 5000 -> 5999 island 6000 -> 6999 lake 7000 -> 7999 river 2nd short Integer value: Latitude in signed minutes (+/- 5400) 3rd short Integer value: Longitude in signed minutes (+/- 10800) POLYLINES: Latitude and longitude data in PNT files are arranged into polylines (or spaghetti). As an example (from MWDB-POLY), France is one polyline. All the lat/lon data points that make up France's coastlines and political borders are in one continuous line. HEADER: The start of a new polyline is Indicated by a header value that is greater than 5. The list above, indicates all the possible polyline starting values. DATA LEVEL: The data level (1 -> 5) determines the amount of detail in your map. When writing programs using this data, level 1 is full detail and level 5 is the least amount of detail. Level 1 -> plot all data points => 1 Level 2 -> plot all data points => 2 Level 3 -> plot all data points => 3 Level 4 -> plot all data points => 4 Level 5 -> plot all data points = 5 The start of each new polyline is understood to be at level 5. The end of each polyline will be at level 5. NOTEs: Because the Short Integer is used, all latitude and longitude values are ROUNDED TO THE NEAREST MINUTE. This limits the usefulness of this data to small scale maps only. Multiply the 2nd or 3rd short integer values by 2.908882086657222D-04 to go from signed minutes straight to Radians. Divide the 2nd or 3rd short integer values by 60 to go from signed minutes straight to Decimal Degrees.