The general approach for creating the AXIOM Beta hardware and PCB stack design was to give every board a clear core purpose and not just pack as many things onto each board as possible just because there was space left. This way each board can be replaced without affecting the rest of the PCB stack - for example as the interfaces between the boards are predefined a new image sensor can be implemented by just changing the Sensor Board. This gives the entire assembly a very sustainable future as any board that is not up to date anymore can be replaced by a newer one and any board that breaks for whatever reason can be swapped without requiring to change the rest of the boards in the camera.
The AXIOM Beta has two high speed module slots with PCIe connectors (these are not really PCIe cards, we just utilize PCIe for the connectors). Each module has a total bandwidth to/from the main processing FPGA of at least 6 Gbit/s. This makes the modules perfect for dealing with high bandwidth video outputs like HDMI/Displayport/SDI. Due to the flexibility this could also allow to create a solid state media recorder as a module in the future. For now the AXIOM Beta relies on external recording though.
The name shields was inspired by the Arduino plugin boards that are also called "shields". The AXIOM Beta sports two shield slots with space for connectors going to both sides of the camera. In contrast to modules the shields in the Beta have slow and medium speed interfaces to the main processing FPGA and therefore are perfect for tasks like: trigger IN/OUT, genlock IN/OUT, timecode IN/OUT, sync IN/OUT or connecting external sensors or buttons, LCDs, etc.