Documentation of open-source simulation - addressing multiple points of interest

As with all large software projects, the support demands of a diverse community of a simulation tool exceeds the means of supply.  Interested parties may be users (from novices to experts), support staff (e.g. computing infrastructure technicians, QA specialists), researchers who wish to use or extend a feature of the software, other (possibly remotely located) members of the development team or validation groups who what to ensure equivalence of models. An open source model for simulation software poses particular challenges. Resources are limited, many developers may never physically meet, and the user community includes novices and those who push at the limits of the virtual physics. Open source supports the discovery of application details yet it does not yet seem to have adopted a business model that is able to amalgamate, preserve and distribute what gets discovered.  Although focused on ESP-r, many of the issues raised in this paper are generic and may have a wider applicability.