The Numerical Electromagnetic Code - Basic Scattering Code is a user- oriented computed code for the analysis of the far field patterns of antennas in the presence of perfectly conducting metal structures at UHF and above. The analysis is based on uniform asymptotic techniques formulated in terms of the Geometrical Theory of Diffraction (GTD). Complicated structures can be simulated by arbitrarily oriented flat plates, an infinite ground plane, and a finite elliptic cylinder. A wide range of practical problems can be simulated using these shapes. For example, flat plates can be used to model the superstructure of a ship, the body of a truck, or the wings and stores of an aircraft. The finite elliptic cylinder can be used to model a mast or smoke stack of a ship, or the fuselage and engines of an aircraft. This document describes the FORTRAN coding in detail. It gives background on practical aspects of the GTD and contains an overview of the code organization. This information will be of primary interest to someone attempting to modify the code. It will also be helpful when the code is being implemented on a computer system on which the coding may not be compatible.