What function does the list of files at the beginning of a ptx file serve?

I was wondering which of these files is necessary and what their function is, so that I can write hand written PTX files and then load them with cuModuleLoad, and cuModuleGetFunction. The out put of the compiler is:
.file 1 “C:/Users//AppData/Local/Temp/tmpxft_00000124_00000000-10_kernel.cudafe2.gpu"
.file 2 “C:/Program Files (x86)/Microsoft Visual Studio 9.0/VC/bin/…/…/VC/\INCLUDE\crtdefs.h”
.file 3 “C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin/…/include\crt/device_runtime.h”
.file 4 “C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin/…/include\host_defines.h”
.file 5 “C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin/…/include\builtin_types.h”
.file 6 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\device_types.h”
.file 7 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\driver_types.h”
.file 8 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\surface_types.h”
.file 9 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\texture_types.h”
.file 10 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\vector_types.h”
.file 11 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\builtin_types.h”
.file 12 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\host_defines.h”
.file 13 “C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin/…/include\device_launch_parameters.h”
.file 14 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\crt\storage_class.h”
.file 15 “C:/Program Files (x86)/Microsoft Visual Studio 9.0/VC/bin/…/…/VC/\INCLUDE\time.h”
.file 16 "E:/junk/Working-
-pc-3068-1300-1/kernel.cu”
.file 17 “C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin/…/include\common_functions.h”
.file 18 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\math_functions.h”
.file 19 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\math_constants.h”
.file 20 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\device_functions.h”
.file 21 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\sm_11_atomic_functions.h”
.file 22 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\sm_12_atomic_functions.h”
.file 23 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\sm_13_double_functions.h”
.file 24 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\sm_20_atomic_functions.h”
.file 25 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\sm_20_intrinsics.h”
.file 26 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\surface_functions.h”
.file 27 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\texture_fetch_functions.h”
.file 28 “c:\program files\nvidia gpu computing toolkit\cuda\v4.0\include\math_functions_dbl_ptx3.h”

This is a debugging directive that records which source files were picked up to produce the resulting PTX code. If you generate your own PTX code, you don’t need to include this information, but it might be helpful.