Assembly allocations enables a component job in one assembly to feed into a component job in another assembly or to feed an independent job.  In the example below, there are two assemblies; A, B, C, D, E, F and G and a second assembly AA, BB, CC, and EE.  In the first assembly, component D not only feeds component B in the same assembly, but it also feeds component CC in the second assembly:

The link between D and CC is a BOM Link.