COVISA extends IRIS Explorer to multi-user visualization. IRIS Explorer was originally designed as a single-user system. To create a visualization, the scientist or engineer wires a pipeline of modules together in the Map Editor. The possibllities for collaboration are very limited: images or VRML models can be sent to fellow scientists, but there is no scope for live collaboration. The COVISA suite of modules transforms IRIS Explorer into a multi-user environment. Individual users each run their own instance of IRIS Explorer, creating their own pipelines. The collaboration is `programmed' by wiring in the new COVISA modules which allow data to be passed from one pipeline to another. In effect, this creates a single shared environment of inter-connected pipelines. The MShare modules allow parameter, geometry, lattice or pyramid data to be transferred between pipelines. For example, a user can connect in an MShareGeom module to their pipeline at an appropriate point, and have the geometry data transmitted to a companion MShareGeom module on another user's pipeline. This allows a variety of collaborative scenarios: an expert user can program the major part of the visualization, simply transferring the final data or image to their collaborators collaborators with different expertise can take charge of different parts of a visualization: in computational steering for example, the computational scientist might control one part, the visualization scientist another full collaboration where each person runs their own version of a common pipeline, but share control of the parameters of each module tutor mode, where the new MAdvisor module allows a trainer to launch modules, or sets of modules, in a trainee's map editor Essentially the collaboration is programmable to achieve whatever scenario the group want. There are two modes of operation: programmable (or on-the-fly) collaboration, where the collaborators connect modules into their pipelines using the map editor; and end-user collaboration, where applications are constructed using the COVISA suite, but packaged into a simple interface with the map hidden. This is the first extension of a modular visualization system to collaborative working. It was designed during the EPSRC-funded COVISA project at the University of Leeds and is described in: Jason Wood, Helen Wright and Ken Brodlie, Collaborative Visualization, Proceedings of IEEE Visualization 1997 Conference, edited by R.Yagel & H.Hagen, pp253-259, ACM Press. The original version was designed for use with UNIX systems; an NT version is now available and will be released on the CD with IRIX Explorer 4.0.