NAQU is an abbreviation of "NOTICE ADVISORY TO QZSS USERS".
It is the QZSS version of the NANU(NOTICE ADVISORY TO NAVSTAR USERS) which the US Coast Guard Navigation Center gives out for information on GPS.
NAQUs are announced from the MCS to the users to give information of the QZSS status. They include: outage of service, reports of anomaly, forecast of events, etc.
Users will get NAQU messages to read in this web page or to follow the Twitter account: "@QZSS_Status".
The cell color of the list means below.