**Guide Section: UNITS** | **EASAP Tree: USER INTERFACE **→** UNIT MANAGER** → **USER UNITS** → **DIMENSIONAL GROUP**

Once a **DIMENSIONAL GROUP** has been defined, additional units beyond the base unit can be defined by adding a **Child CONVERSION**. Each **CONVERSION** defines a new ‘Unit’ and the method for converting from the **BASE UNITS** to the new Unit.

- There are two methods available for performing the conversion,
- Set
**Factor:**to a number to multiply the**BASE UNIT**by - Set expressions for
**Base to Unit:**and**Unit to Base:**parameters

The main example for the second method is temperature conversions. Let’s look at converting from **F** back to **K**.

The expressions to use are as follows:

**Base to Unit:**(1.8***value**) - 459.67**Unit to Base:**(**value**+459.67)/1.8

In the first expression, the special object reference ‘**value**’ refers to the Base unit (**K**), while in the second expression, ‘**value**’ refers to the Unit (**F**).

CONVERSION | |
---|---|

Essential Parameters: | |

Unit: | Name of new UNIT |

Optional Parameters: | |

Base to Unit: | Expression using 'value' to represent BASE UNIT that converts from BASE UNIT to new UNIT. |

Unit to Base: | Expression using 'value' to represent new UNIT that converts from new UNIT back to BASE UNIT. |

Factor: | Factor to multiply BASE UNIT by to convert to UNIT |