I am not expert in Diameter based protocol or 3GPP defined various Diameter based applications. But I have some level of understanding and would like to try answer your query.
There is concept of traffic detection function (TDF) at PCEF side. It can detect various events specific to a particular application such as start/stop of an application. TDF takes Application Detection and Control (ADC) as input. These ADCs can be configured at TDF by using following two methods under the solicited application reporting:
1. Dynamic ADC : In this method, PCRF configures ADCs dynamically at the TDF/PCEF through Credit-Control-Answer (CCA) , (Re-Auth-Request) RAR or TDF-Session-Request (TSR) messages.
2. Pre-defined ADC: In this method, ADCs will be pre-defined at TDF/PCEF and PCRF node activates/deactivates ADCs at TDF. To optimize the number of activation and de-activation message exchange, group of ADCs can be created. This way PCRF can activate/deactivate a group of ADCs together.
This is the way of solicited application reporting by using the ADC-Rule-Report AVP in the CCR message. CC-Request-Type AVP would carry either UPDATE_REQUEST or TERMINATION_REQUEST within the CCR message.
Since CC-Request-Type AVP can be either UPDATE_REQUEST/TERMINATION REQUEST, Framed-IP-Address AVP might be included in case of TERMINATION_REQUEST because Framed-IP-Address AVP is included in the CCR message when either IP address is allocated or released. As part of TERMINATION_REQUEST request, IP address can be released but not sure for the UPDATE_REQUEST that IP address can be allocated.