For modelling and simulation purposes there are numerous software packages currently in use in the pulp and paper industry. In general terms, it is possible to subdivide them into three groups: 
and thus providing the full functionality and at the same time safeguarding the undisclosed code (Maybock, 2004). In line with this, big equipment suppliers like Andritz and Metso have bought companies that develop flowsheet-oriented software. Now, only a few software suppliers are independently active on the market.
• Software for data analysis and data-based modelling and simulation— This type of software is typically applied in cases where no physical models are available or even the question of cause and effect is unresolved. Data analysis followed by modelling can be performed as described earlier. Typical examples are wet end chemistry modelling issues. A typical example for this type of software is Matlab (mathworks) (Mathworks, 2002, 2005).