5  Data access

cm_setup(), cm_connect(), and download_nc() coordinate optional Copernicus acquisition without storing credentials. read_nc() opens a local, read-only NetCDF descriptor. No OPeNDAP, THREDDS, cloud store, or write support is claimed.

A NetCDF backend validates file identity, maps physical axes to the canonical contract, and reads only requested blocks when possible. cube_collect() explicitly materialises values.