There are two ways that conversions can be defined.

A straightforward conversion that just requires a re-scaling can be defined by just selecting the two units and defining the scaling factor. This automatically generates the conversion expression for converting in both directions, e.g. Pounds to Dollars and Dollars to Pounds. This is referred to as the Simple method.

More complex situations, like converting Fahrenheit temperatures to Celsius, cannot be done with just a scaling operation. In these situations you must define the conversion in each direction separately. This is referred to as the Complex method.

Simple method

From the standard menu (as initially installed) select: Favourites | Functions | Standing Data | Units | Unit Conversions. This will present you with a list of all the conversions available.

Press the New button in the Simple group to define a new scaling conversion. This will present you with a form that allows you to select the two units that are to be converted and the scaling factor to use. Make sure you get the scaling factor right and the units the right way round.

Pressing the Swap To/From button will swap the 'to' and 'from' units. This can be useful to allow you to define the scale in a natural way. For example, say you wanted to convert between metres and centimetres. The 'natural' scaling factor is 100, but only if you define the 'to' units as centimetres, otherwise it's 0.01.

Press Save to make your selections permanent.

Complex method

From the standard menu (as initially installed) select: Favourites | Functions | Standing Data | Units | Unit Conversions. This will present you with a list of all the conversions available.

Press the New button in the Complex group to define a new conversion. This will present you with a form that allows you to define all the characteristics of all types of conversion.

Note: In this form, you are only defining the conversion in one direction. You need to create two conversions to go in both directions, e.g. Fahrenheit to Celsius is one and Celsius to Fahrenheit is the other. Make sure they are self consistent otherwise you'll get strange conversion results. When a unit is converted one way and then back again it should end up the same as it started!