When checked executables or DLLs are built using this procedure, the files contain their external symbols by default. Thus, the symbols are available to the debugger as soon as the program or DLL is loaded. When free executables or DLLs are built, symbol files with the filename extension .dbg are put in the same directory as the built executables.
It is possible to get line-number (local) information in the image files using BUILD. However, this is not the default since it would have a severe impact on disk space requirements needed to build the system. This information can be included by setting the NTDEBUG environment variable as follows:
set NTDEBUG=ntsd
Setting this environment variable causes BUILD to generate .obj files and image files with full symbolic debugging information.