In the Flex SDK, what are the "extra" .swc files in the libs directory that don't have matching signed framework RSLs?

Taking the specific example of SDK 4.5.0.20967, the SDK includes the following signed framework RSLs (.swz files) in "<sdk_path>\frameworks\rsls":

  advancedgrids_4.5.0.20967.swz
  charts_4.5.0.20967.swz
  framework_4.5.0.20967.swz
  mx_4.5.0.20967.swz --------> matching .swc is in libs\mx\mx.swc
  osmf_1.0.0.16316.swz
  rpc_4.5.0.20967.swz
  sparkskins_4.5.0.20967.swz
  spark_4.5.0.20967.swz
  spark_dmv_4.5.0.20967.swz
  textLayout_2.0.0.232.swz

The .swc files in the matching libs directory "<sdk_path>\frameworks\libs" are:

  advancedgrids.swc
  authoringsupport.swc ---> no .swz match
  charts.swc
  core.swc ---------------> no .swz match
  flash-integration.swc --> no .swz match
  framework.swc
  osmf.swc
  rpc.swc
  spark.swc
  sparkskins.swc
  spark_dmv.swc
  textLayout.swc

So 9 of 10 .swz files match the ..\开发者_如何学编程libs\*.swc exactly, with the one .swz -> .swc mismatch being mx.swc which is one subdir below.

What I'm mainly wondering about is the seemingly extra .swc files:

  authoringsupport.swc
  core.swc
  flash-integration.swc

What are they, and are they needed in a basic flex project? Documentation on them is sparse/non-existent.

I expect that the question may be a bit misguided and the existence of those three .swc files in the root of the frameworks\libs directory is somewhat irrelevant. However, the reason I was initially looking at this is that the IDE I'm experimenting with (Amethyst) seems to, at least, be including all .swc files it finds in the frameworks\libs directory into the project and I want to determine what I can manually remove.

These are default Adobe packages that enable things like bindings.

Best bet for figuring out what is required in your project because it's being implemented is to remove one at a time until your project fails to compile, and then restore them.