A method of modelling at least a part of a gas turbine engine, the method comprising: generating a mesh for a feature using at least one data entity of a data structure, the at least one data entity defining a geometrical shape of the feature, wherein the data structure comprises: a set of data entities defining geometrical shapes of features; and modelling attributes associated with the geometrical shapes of the features; and assigning one or more modelling attributes using the modelling attributes associated with the geometrical shapes of the features.