This section describes the organization of the source files. Its contents are not necessarily relevant for the binary distribution. The section is probably most useful to those readers who want to be able to extend or who want to do maintenance on YODL's sources, or who want simply to understand what's happening inside the YODL program. Much of the documentation is provided in the individual source files themselves. This section, however, should offer the `broad picture', allowing you to understand the logic behind YODL relatively fast.