The debug listing is a specially prepared source code listing that lets you set breakpoints and follow the course of procedure execution in an application. It is an expanded listing file that the ABL compiler creates during procedure compilation.

The format of a debug listing is similar to the standard ABL compiler listing. Like compiler listings, debug listings expand all preprocessor, include file, and parameter references. The main difference is that the text in debug listings contains only numbered source code lines without headings, page formatting, or any of the other internal data information (such as buffer and frame use) usually provided by compiler listings.

Line numbers appear in the source code pane if you select the Include Source Line Numbers option in the Preferences dialog box. For more information, see Preferencesdialog box. The Debugger displays line numbers by default.

The Debugger displays the listing for the executing procedure each time it receives control (for example, at a breakpoint). If the Debugger cannot find the debug listing for the procedure, it tries to generate it from the procedure source code. If the Debugger can find only the r-code for the procedure, it displays the procedure name and line number in the status bar as you step through the procedure.

For more information on procedure source files and debug listing files derived from procedure files, see Debugger files.