This inlcudes both manual user input but also any other external data (network, files, etc.). This makes it necessary to provide always the same external data to the environment for every evaluation-rendering of an object.
To make the rendering comparable, we have to make sure that the object is rendered under the exact same conditions, too remove the possibility of side-effects in the rendering resulting from object behaviour instead of changes in the rendering environment. As this is not possible for emulation environments (where the digital object remains unchanged), we have to extract information about the rendering from the environment. When digital objects are migrated to a different format, the significant properties before and after the migration are usually compared to check for differences in the rendering. This creates the necessity to evaluate the results of digital preservation actions involving emulators, to make sure that renderings of digital objects stay true to the original once they are replayed at a later point in time. Emulation is one of the main strategies for preserving digital objects.
