In Central CTS (cCTS), what is the ‘the System’ concept and its two key grouping structures?

Central CTS introduces ‘the System’ to glue cross-system technical components into collections that move through the landscape as a whole:

• A transport cluster groups systems by role (DEV cluster, QAS cluster… each holding all products of that role, with its own SID in TMS).
• A transport collection holds all entities (transport requests from different systems) needed to satisfy one requirement.