Creating an Expression

Note: The procedures for creating expressions in the Filter tab and in the Sample Definition > Group Set tab > Expression Editor window are virtually identical. The only difference is that the Expression Editor window has Validate and OK buttons while the Filter tab has a Save button. The Filter tab is displayed in the main Forsta Plus window, so clicking Save checks the expression and saves the changes; it does not close the window. However as the Expression Editor function opens in a separate window, clicking OK checks the expression, saves the changes and automatically closes the window. If you then wished to make further changes to the expression, you would need to reopen the window before continuing. The Validate button is therefore included to allow you to check that the expression you have entered is valid before you click OK to save it and close the window. Therefore, if you are creating an expression in the Expression Editor window, click Validate to check the expression before you click OK to close the window.

1. In the left column, search for or browse to the criteria you wish to start your expression with, and click on it to select it.

Any options that may apply to the criteria will be listed in the second column.

2. Select the radio button for the None operator (you cannot start an expression with the operators And or Or).
3. Select the appropriate function and type any text or values into the Text or Number fields as required.
4. Click Add Here(see the following figure) to add the criteria to the field - .



Figure 1 - Adding criteria to the data field

Note that the coding is displayed in the white data field while the logical expression is “written” below the field.

5. Select and add criteria until you have the required expression - .



Figure 2 - Example of a complete expression

6. Click Save to save the changes.