Data Fields
uint16_t	attr_len
	Length of the received attribute data.
uint32_t	attr_id
	Classification of the attribute type. For example, "Title" or "Date".
uint8_t *	p_attr_data
	Pointer to where the memory is allocated for storing incoming attributes.

• components/ble/ble_services/ble_ancs_c/nrf_ble_ancs_c.h