Here is a list of all macros with links to the files they belong to:

__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES : vtkCocoaMacOSXSDKCompatibility.h
_vtk_add_event : vtkCommand.h
_vtkDAIMUnused : vtkDataArrayIteratorMacro.h
_vtkGetSymbolNameAsString : vtkResourceFileLocator.h
_vtkGetSymbolNameAsString_I : vtkResourceFileLocator.h
_vtkGetSymbolNameAsString_II : vtkResourceFileLocator.h