Modifying animation using a metadata file containing parameter information

A method of generating an executable graphic file for an animation. Graphic data [604] defines first characteristics of an animation, which are accessible via locked parameters at a first level of user access. The graphic data [604] also contains references to unlocked parameters stored as metadata [605] in a metafile [801]. The metadata [605] includes, for each unlocked parameter, a value field [907], a range of possible values [909, 910] and a description [913], thus making it possible to construct a user interface [1301] to modify second animation characteristics without modifying the graphic data [604]. The graphic data [604] is combined with rendering instructions [603], to form an executable animation file [2902]. Preferably the executable file [2902] cannot execute after a predetermined date. Multiple instances of the animation are created by re-use and modification of the original metafile [801].