The SOURCES_USED macro indicates that there is another Sources file or make file elsewhere in the tree. You must use this macro if that additional file contains build dependencies.
When you specify the following, the NMAKE utility regenerates the objects file when changes occur in the Sources file that is located in the specified directory:
the NMAKE utility will also regenerate the objects file when changes occur in any Sources file or make file that you specified in the SOURCES_USED macro.
For example, a Sources file typically includes some other file. Just beneath that directive you could specify:
This instruction establishes a link between that file and the Sources file. When that other file changes, the NMAKE utility regenerates the _objects.mac file.
Build date: 5/3/2011