The Control Structure Diagram (CSD) is an algorithmic level diagram automatically generated for Java, C, C++, Objective-C, Ada, and VHDL source code. It is intended to improve the comprehensibility of source code by clearly depicting control constructs, control paths, and the overall structure of each program unit. The CSD fits into the space that is normally taken by indentation in source code. It also provides "handles" for code structures, which enable meaningful source code folding and other structure-related editing features.