Data Request XML format

The Data Request defines the diagnostics which are requested from modelling centres participating in the sixth phase of the Climate Model Inter-comparison Project (CMIP6). The Data Request is presented as two XML files: a configuration file and the content. Each file has an associated XSD schema. The XSD schema for the content file is generated automatically from the configuration file. For many users it will be more convenient to deal with the python interface or web and spreadsheet versions of the request, which will be described in a separate document. The transformation to an XML format from the traditional spreadsheet format is designed to deal with a number of issues associated with growing complexity and a need to support automation driven by the scale of the request. In order to preserve continuity, many of the records in the XML files will have a direct relation to spreadsheet rows in the traditional format. A separate document describes a simple python API for the data request