  The Global Accelerator Network is a proposed model for remote operation of a
future large accelerator by the partners of an international collaboration. The
remote functionality would include not only routine operation and machine
studies, but also hardware diagnostic tests and software maintenance and
development, so the control system must offer both high and low level remote
access to the accelerator and its components. We discuss in this paper some of
the special requirements, and how they might be satisfied using current or
developing technology, such as web-based applications and industrial automation
standards. The choices made must be acceptable to the collaboration, but will
also have a strong influence on its effectiveness. The biggest technical
challenge is likely to be the middle layer software which is responsible for
system integration, automation, and presentation of the machine state to the
operating staff.
