| 14 | === Derived Coordinate === |

| 15 | |

| 16 | A derived coordinate links together explicit coordinate instances of a Field with a defined process for combining these to form a new coordinate. |

| 17 | |

| 18 | Each input coordinate is named and a derivation formula is provided. At present derivation formulae are provided by named reference to [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/apd.html Appendix D] and [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/apf.html Appendix F] of the CF conventions for NetCDF files. |

| 19 | |

| 20 | These transform constructs correspond to the functions of the CF-netCDF attributes `formula_terms`, which describes how to compute a vertical auxiliary coordinate variable from components ([http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#dimensionless-v-coord CF Appendix D]), and `grid_mapping`, which can describe how to compute true latitude and longitude auxiliary coordinate variables from horizontal projection dimension coordinates ([http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#appendix-grid-mappings CF Appendix F]). |