TStep was designed to be very flexible. Two portions of the code serve as the skeleton. The main program TStep responds to the input data and controls the logical flow of the program, and the subroutine TSdyn controls the logic of the particle dynamics calculations. We continue to add new capabilities to TStep, some at the request of users.
The input data define the transport system, specify the control logic, and specify the input and output options. All linear dimensions and coordinate values are in centimeters. Sections that describe the input lines will define the units for other parameters. Each line recognized by TStep consists of a keyword followed by various parameters. The keyword determines the action taken by TStep. The order of the keywords is unimportant except as noted. For example, the elements in the transport system must appear in the proper sequential order. Some keywords define beam-line elements, described by three or more parameters. The first three parameters have the same meaning for all elements:
1. The length L of the element,
2. The radial aperture size Ra at the downstream end of the element, and
3. An OutputFlag, indicating whether or not to output data at the downstream end of the element.