Umm.. I overlooked the rightmost small pass.

My previous comment to the 'Control Out Handler' is related to the major pass on the right side of the flow chart:
Control Out Handler
- Setup Packet? == No
- - State USB_RECEIVE? == Yes
This pass handles data stage of Control-OUT transfer.

The rightmost small pass:
Control Out Handler
- Setup Packet? == No
- - State USB_RECEIVE? == No
will occur on the status stage of Control-IN transfer.

This table shows the stage of Control transfer.

             Control-IN   Control-OUT  Control-OUT  
             transfer     transfer     transfer (no data stage)
______________________________________________________________
SetUp stage    SETUP        SETUP        SETUP
Data stage     IN           OUT          ---
               ...          ...
               IN           OUT          ---
Status stage   OUT          IN           IN

In this table, SETUP and OUT transaction is handled by Control-Out EP (interrupt).
IN transaction is handled by Control-In EP (interrupt).
Correspond these transaction sequence and the flow chart.

Control transfer is the most difficult part to understand for beginners: only Control transfer has stages. Other transfer type, interrupt/ bulk/ isochronous are easier: only a sequence of the same transaction, IN or OUT.

Tsuneo