Inner Code
The squads can create libraries, components, pieces of code, whatever, that can be used for other squads.
Ex.: Squad A has created a lib, then Squad A becomes the maintainer of it. However, if the Squad B uses Squad A's lib and Squad B needs an extra feature, Squad B should ask to Squad A to implement it, if Squad A is to busy to do it, Squad B is free to code adding the extra feature to Squad A's lib in this case Squad A might help Squad B. After implemented Squad B sends the code to be reviews by Squad A.