In addition to transferring isochronous data during each basic cycle, multiple nodes are able to share common time slots for better bandwidth utilization. For that reason, the isochronous phase can distinguish between time slots dedicated to particular nodes that have to send their data every single basic cycle and time slots reserved for multiple slots to transfer their data one after the other.
Less important, yet still time-critical, data can therefore be transferred during longer cycles than the basic cycle. Assigning the time slots during each cycle is at the discretion of the managing node.