The Lock Status Report is used to report the status of a Lock. The report is intended to be originated from shore (e.g., from AIS competent authority or authority operating the lock).

• The Message Linking Identifier (MLID) is used to link this Status Report with a Waterways Management Message (WWM) and Linked Text Message (LTM). Specifically, the WWM message can be used to provide the geographic location and name of the lock for legacy systems that do not have the navigation universal identification (NUID) database.
• The Lock ID is the 4-character NUID as published by the USACE.
• The report is encoded with the time (UTC hour and minute) of the information. The date is assumed to be the date of reception. Since this information time will always lag the time of transmission/reception if the time of the report is later than the current time, then it is for the previous day.
• NUIDs are defined for the locks and for the chambers. If the NUID specified is for the lock in general then the status information is for the lock as a whole. If the NUID is for a specific chamber then the message reflects that status of that chamber.
• The UN-LOCODE is 5 characters with the first 2 being the country; this can be determined from the MMSI country code so just the last 3 characters of the LOCODE are transmitted.
• If Lock/Chamber Operational Status is limited (2) or closed (3) then one of the stoppage codes should be selected. If the lock is operating then stoppage reason shall be set to 0 (no stoppage) – unless a future stoppage is indicated by non-zero times for the projected stoppage time fields in which case the stoppage code is for the planned outage.
• Only a few codes have been defined so far for special locking instructions; more will be added later.
• Delays of longer than 4 hours should not occur unless there is a stoppage.
• Although gauge and weather and temperature could be transmitted via an environmental message, they can be included here for ease and compactness (the gauge trend value is also not supported by the environmental messages).
• If the lock operator knows of an upcoming stoppage this can be reported by filling in the projected time of stoppage start time fields. If these fields are used then a lock stoppage code can be selected to indicate why the lock will be closed. If no stoppage is planned, then these fields shall be set to not available.
• If there is a current or planned outage then the Date/Time for return to full operation fields are used to indicated when the lock will be back to normal operations. If there is no current or planned outage these fields shall be set to not available.