Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
"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: