1. A method of converting elements of a file that is based on a first standard to elements of a file that is based on a second standard, the standards being IEC 61970 and IEC 61850, a file in IEC 61970 being coded according to CIMXML (RDF Schema) and a file in IEC 61850 being coded according to SCL (XML Schema), the data in each file being modelled by using a UML model for the corresponding standard, and the conversion being performed by using mapping rules generated based on the UML models of the two standards and a UML model of mappings between the two standards; comprising: selecting at least one element of the file that is based on the first standard; identifying and selecting all the elements referenced by the at least one selected element; recursively identifying and selecting all the elements referenced by the previously selected elements until none of the selected elements reference any element that is not selected; converting the selected elements, the conversion being performed by using the mapping rules, and applying post-processing rules to the converted elements to generate the file that is based on the second standard.