There is a description in the document “DWM1001 System Overview” especially in section 4 “DRTLS Network, Configuration and Control”. As you can see, there are only three Types of devices anchors, tags and gateway, there is no differentiation between tags that send position and tags that do not send position. As you can see there is a single “Superframe structure” and particularly this sentence “At the end of the ranging exchange the tags can either receive 34B data from the network or send 34B to the network through the gateways”
That means that when no ranging is ongoing there would probably be no IoT data frames exchanged.
This is my interpretation, please have a closer look and read of the documentation and keep in mind that the PANS lib is not very flexible in terms of functionality and target one use case.
An additional note, when it comes to user data it is also possible to use an nRF52 back channel like they do for configuration with BLE, see BLE API on section 7.