technology continues to be developed by Raymond van Diessen (IBM) to include dynamic objects by exploiting the communication facility between the UVC program and a future application. Alternative emulation approaches Other emulation approaches are stacked emulation, migrated emulation and Emulation Virtual Machine (VM). Stacked emulation Stacked emulation is platform dependent emulation that requires, over time, multiple emulators running on top of each other to reconstruct a historic platform. This brings better performance and functionality but lacks compatibility between platforms. This approach can mainly be found in the gaming industry. Migrated emulation Migrated emulation involves creating a platform dependent emulator that must be migrated (adapted) to subsequent newer hosts. When the particular operating system on which the emulator is created becomes obsolete, the emulator is translated to run on the new current platform. This approach is a strategy with high risks Emulation Virtual Machine (EVM) The EVM was presented by Jeff Rothenberg in 1999 and involves introducing an additional layer between the host platform and emulator and is said to be platform and time independent. This approach uses a virtual machine, and an emulator specification interpreter. It is said to be platform and time independent. It is quite complex as an emulation specification needs to be written for the computer platform on which the original software runs. The specification is then interpreted by an emulation specification interpreter that creates an emulator for the old platform. Both the interpreter and the created emulator run on the EVM. Cost implications Copyright issues Copyright issues for this approach are not expected to be different from those of any other approach. If intellectual property rights exist for a format this issue has to be taken up with the format owners. Similarly, to 'UVC-enable" applications the source code is required from the developer and therefore permission from the owner. Lastly, for hardware emulation, all the relevant licenses of the software running on the system are required. Historical timeline 1995 Rothenberg advocates emulation as a long-term preservation solution. 2000 Rothenberg describes an Emulator Virtual Machine (EVM) 2001 Lorie presents a novel approach to the preservation of digital data, based on a Universal Virtual Computer 2002 Lorie reports on the ongoing work in refining the methodology and building an initial prototype. 2002 Proof of concept for UVC-based preservation of static files 2004 Experimental stage of implementing a UVC for images within an operational digital archive environment 2005 Operational