1# Common Events of the NFC Subsystem 2This document lists the common system events provided by the NFC subsystem to applications. Applications can use [APIs](../js-apis-commonEventManager.md) to subscribe to common system events. 3 4## COMMON_EVENT_NFC_ACTION_ADAPTER_STATE_CHANGED 5Indicates that the state of the device NFC adapter has changed. 6 7- Value: usual.event.nfc.action.ADAPTER_STATE_CHANGED 8- Required subscriber permissions: none 9 10When the state of the device NFC adapter changes, the event notification service is triggered to publish this event. 11 12## COMMON_EVENT_NFC_ACTION_RF_FIELD_ON_DETECTED 13Indicates that the NFC RF field is on. 14 15- Value: usual.event.nfc.action.RF_FIELD_ON_DETECTED 16- Required subscriber permissions: ohos.permission.MANAGE_SECURE_SETTINGS 17 18When the NFC RF field becomes available, the event notification service is triggered to publish this event. 19 20## COMMON_EVENT_NFC_ACTION_RF_FIELD_OFF_DETECTED 21Indicates that the NFC RF field is off. 22 23- Value: usual.event.nfc.action.RF_FIELD_OFF_DETECTED 24- Required subscriber permissions: ohos.permission.MANAGE_SECURE_SETTINGS 25 26When the NFC RF field becomes unavailable, the event notification service is triggered to publish this event. 27