  Since 2005 ESO has been working with its community and industry to develop an
extremely large optical/infrared telescope. ESO's Extremely Large Telescope, or
ELT for short, is a revolutionary ground-based telescope that will have a
39-metre main mirror and will be the largest visible and infrared light
telescope in the world. To address specific topics that are needed for the
science operations and calibrations of the telescope, thirteen specific working
groups were created to coordinate the effort between ESO, the instrument
consortia, and the wider community. We describe here the goals of these working
groups as well as their achievements so far.
