Why has SBML Level 3 taken so long to define?
SBML Level 3 actually has a long history. It was originally intended to be SBML Level 2, and was discussed as such at workshops through 2002. At the 5th SBML workshop, a consensus emerged on the following points: (1) the planned changes between SBML Level 1 and the then-called Level 2 were too great, (2) a smaller step should be taken to introduce the use of MathML and other changes in SBML, and (3) the then-planned Level 2 features should be pushed to SBML Level 3. Originally, the Caltech ERATO Team lead the organization of SBML and wrote the final SBML specifications, but they were also involved in developing the Systems Biology Workbench (and indeed, this was their primary objective at the time), which meant that their time was not spent entirely on SBML work. In the late 2002 to 2003 time period, there were (in short order) personnel changes in the team, a need to write grant proposals to support further SBML work, and an explosion in interest in SBML (which led to time spent on mo
