ANALYSIS_CONTROL and BUILD_JOB recognize three types of modules: Input, Output and Normal. Input modules are those sub-programs that perform the input of data to the program. Examples of input modules are the routines to read events from disk or tape, the routines to read events from the online global event buffer, and the routines used to create Monte Carlo events. ANALYSIS_CONTROL requires that at any time one and only one input module be active. More than one such module can be linked concurrently, however, and the user can switch between input modules inside the executable program.
Output modules are those that perform the Output of data from a program. Most of the requirements of CDF may be met by a single output module, but the possibility of more specialized ones has been retained.
Normal modules are typical analysis sub-programs. The majority of modules in the system will fall into this category. This note is intended to provide a guide to authors of normal modules. People interested in writing input or output modules should consult appendix B and Liz Sexton-Kennedy.