cfdm: A Python reference implementation of the CF data model

The cfdm open-source Python library implements the data model of the CF (Climate and Forecast) metadata conventions and so should be able to represent and manipulate all existing and conceivable CF-compliant datasets.The CF conventions are designed to promote the creation, processing, and sharing of climate and forecasting data using Network Common Data Form (netCDF) files and libraries. They cater for data from model simulations as well as from observations, made in situ or by remote sensing platforms, of the planetary surface, ocean, and atmosphere. For a netCDF data variable, they provide a description of the physical meaning of data and of its spatial, temporal, and other dimensional properties. The CF data model is an abstract interpretation of the CF conventions that is independent of the netCDF encoding.The cfdm library has been designed as a stand-alone application, e.g. as deployed in the pre-publication checks for the CMIP6 data request, and also to provide a CF data model implementation to other software libraries, such as cf-python.