atlc is a program designed for finding the properties (characteristic impedance, inductance per meter, capacitance per meter, velocity factor, electric field distribution) of any transmission line with 2 or 3 conductors (i.e. a normal line or coupler). It uses the finite difference method to determine these properties, and can handle any cross section. The program atlc needs to know shape of the transmission line's cross section. This cross section is stored in a data file, which happens to be a Windows bitmap file. The bitmap file is read by atlc, following which the program performs the analysis. Look in /usr/local/share/examples/atlc for some examples.