Displaying Elements of a Custom Data Type
When you are using interface elements such as the Watch window, the Visual Studio debugger automatically expands common data types to show their most important elements. If you have your own custom data types that you want the debugger to autoexpand, you can add rules to the file autoexp.dat, which is located in the \bin directory. Instructions on how to write autoexp rules are located in the file itself.
Note The structure of this file and the syntax of autoexp rules may change from one release of Visual Studio to the next.
Instead of using autoexpand.dat to control autoexpand rules in managed code, the managed expression evaluator uses mcee_mc.dat for Managed Extensions for C++ and mcee_cs.dat for C#. You can find these files in the debugger package directory.