### Table of Contents

# Sub-set index list

A sub-set index list contains only a sub-set of the indices of another index list. One example of a sub-set is the built-in *radionuclides* index list.

One of the main uses of the sub-set index list is to remove unnecessary indices from the computations.

## Example

Consider a model which deals with different types of pesticides. Thus, a material is created for each pesticide. Important when modeling pesticides is also the water content, so water transport must be modelled as well.

Materials |
---|

DDT |

ametryne |

nicotine |

propham |

Water |

The equations for water transport are naturally very different from those of pesticide evolution, and for simplicity the model is divided into two parts.

Here two sub-sets of the *Materials* index list can be made: one sub-set that contains only water, and one containing the pesticides. The equations for water transport are given the *Water* sub-set index list and the others are given the *Pesticides* sub-set.