"A Dataset Query Capabilities (DQC) document is an XML document that describes the set of requests that can be made to a THREDDS data service. A DQC document is returned when a THREDDS dataset is accessed with serviceType "QueryCapability". The DQC can be thought of as an abstract description of the contents of a THREDDS dataset."
http://www.unidata.ucar.edu/projects/THREDDS/tech/dqc/DqcSpec.html
thredds
archives: