A user equipment, UE, Radio Capability identifier, ID, operation method, performed by a first communications device and comprising: deleting a UE Radio Capability ID in a case that a first condition is met; and/or retaining the UE Radio Capability ID in a case that a second condition is met; characterized in that the first condition comprises at least one of the following: none of UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and none of UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and none of UE Radio Capability IDs in a source network are applicable to a target network; and the second condition comprises at least one of the following: all UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and all UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and all UE Radio Capability IDs in a source network are applicable to a target network. deleting a UE Radio Capability ID in a case that a first condition is met; and/or retaining the UE Radio Capability ID in a case that a second condition is met; characterized in that the first condition comprises at least one of the following: none of UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and none of UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and none of UE Radio Capability IDs in a source network are applicable to a target network; and the second condition comprises at least one of the following: all UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and all UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and all UE Radio Capability IDs in a source network are applicable to a target network. none of UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and none of UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and none of UE Radio Capability IDs in a source network are applicable to a target network; and the second condition comprises at least one of the following: all UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and all UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and all UE Radio Capability IDs in a source network are applicable to a target network. all UE Radio Capability IDs in a source network are applicable to a target network; a terminal moves between networks, and all UE Radio Capability IDs in a source network are applicable to a target network; or a terminal moves between networks, a UE Radio Capability ID is received from a second communications device, and all UE Radio Capability IDs in a source network are applicable to a target network.