IRIS Knowledge Base

The IRIS DMC normally receives two copies of Transportable Array data, the real-time telemetered copy and a later "final" copy.  In some cases a third copy of data is received that fills in gaps in the telemetered data.  These different versions of the data are kept separate using SEED quality codes (R, D and Q).  For more information please visit: http://www.iris.edu/earthscope/usarray/#data 

Many DMC data request interfaces allow the user to specify which quality of the data they would like to receive.  The default, "best" quality, is a merge of all qualities available using an order of preference; in this case all overlaps have been pruned out and the data is marked with an M quality code.

Early in USArray the automated pruning of overlaps was not the default request action at the DMC and the merging of qualities could result in small overlaps being returned to the user.  Now the only way to get overlaps is to request all copies of the data explicitly.