A method controls an additive manufacturing apparatus, in which an object is built by consolidating material in a layer-by-layer manner. The method includes receiving commands to be executed by the additive manufacturing apparatus to cause the additive manufacturing apparatus to carry out a build of an object, wherein each command includes an identifier identifying a time during the build at which the command is to be executed, and executing each command on the additive manufacturing apparatus in accordance with the time identified by the associated identifier. Further, an apparatus and a data carrier carry out the method.