- All lines in a same file are of the same width and color
- The first letters of the file name are used by the program:
- "L" means a line file, "F" means a filled area or polygon file
- "L2" will be drawn on top of "L1"
- In "F2M", the third letter "M" is reserved for transparent polygons
- As example: "F1X-Lakes01.plt", "F2M-Cities01.plt", "L3X-Secondary_roads01.plt", "L4X-Main_roads01.plt", etc.