Expression (Add Expression Column)

Expression adds an expression-based schema column to an overlay.

Click on Property/Add and select Expression in the drop-down menu.

Alternative ways to open this command:

1. Maps Control Bar:

Right click on the Overlay’s Schema and open from the Maps Control Bar:

or press Ins on the keyboard.

2. Overlay dialog:

This command can also be accessed from the Overlays dialog > Schema tab > Column drop-down:

This opens the Expression Builder dialog:

You can now create the expression to be added as a schema column.

For example to add the Comparison > Between operation with Low and High area values of 1000 and 2000 as an expression, select Operators > Comparison > Between and enter the Expression values, ie, _area# Between 1000 and 2000:

Click OK.

The Expression column will be added to the Schema:

If required the properties and values for the Expression column can be viewed and edited. To do this right-click on the Expression column and select the local Properties... option:

The Schema Column dialog will be displayed to allow the properties and values to be viewed and edited:

Click OK to save any changes.

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