Priority is a function of data source.  Data which has been checked by CSIRO and which originates with CSIRO is considered the highest prority (1) and forms the basis of all further QC.  This is identified as the Mership data set. In any cases of cast duplication, it is the Mership data which will be kept.  Duplication between casts from other sets are settled by keeping the cast with the lowest priority value.

Priority is linked to the data at the time of conversion from Meds-ascii format or random access (QUEST) format to direct access (IOTA) format.  The programs check whether you wish to add a priority and then allow you to input both the data source and the assigned value for the priority.  If the priority is already associated with a cast, it is not currently overwritten. A warning is printed and the addition of the priority is skipped.

It is stored with each cast in the surface codes group of the Meds-ascii format (see a full description of this format here)and is identifiable by the Srfc_Code = 'IOTA'.  The Srfc_Parm field holds the source of the data (e.g., Mership, BOM, LevitusWOA, Farseas, etc) and the Srfc_Q_Parm holds the value of the priority.  Because of the limitations of the Meds-ascii format, the lowest priority permissible is 9.

The priorities currently assigned are as follows:

CSIRO Mership - 1
BOM - 2
WOCE - 2
Levitus WOA - 7
Far Seas Fisheries data - 7
Noumea SOOP data - 5