XA collection contains datasets and other collections, and sometimes helper objects like places and instruments. Datasets in turn may contain other datasets.
Note: all collections gives a longer list than the one on this page.

XTimes is for datasets where date/time is an essential part of the data, such as in meteorology or oceanography. It is not for reproduceable experiments such as common in physics and chemistry, and is not used for publication dates.

XPlaces is for datasets where geolocation is essential, such as in meteorology or oceanography. It is not for reproduceable experiments such as common in physics and chemistry, and is not for e.g. the laboratory where these experiment are conducted.

XNetCDF is a data format particularly suited for multidimensional blocks of numbers, including metadata about scale, units etc. For some NetCDF datasets, we also provide CDL, NcML and CSV versions.

X For netCDF datasets we offer, besides the usual download, OPeNDAP access. Benefits are: view internal metadata hidden in the data files, make slices and subsamples of data, programmatic access to data with APIs for Java, Python, Matlab, etc. More info: THREDDS, OPeNDAP intro.