Abstract: A system for network data analytics comprising a network data analytics function, NWDAF, and one or more network functions, NF, wherein the NWDAF is arranged to obtain a dynamic event definition, wherein the dynamic event definition defines a custom data analytics function for processing data, and register the dynamic event definition at the one or more NFs, where an NF is associated with one or more NF entrypoints for the data, wherein at least one of the NFs is arranged to receive the dynamic event definition from the NWDAF, verify the dynamic event definition in accordance with one or more pre-determined verification criteria, and, if the verification criteria are fulfilled: assign an identifier to the received dynamic event definition, transmit the identifier back to the NWDAF, and register the dynamic event definition in an event definition store of the NF, wherein the NWDAF is arranged to receive the identifier associated with the registered dynamic event definition from the at least one NF.