The Fields button in the Expression Builder allows you to specify data fields from your Collection. There are two types of fields available for use, Form Fields and Remote Fields. Form fields are the data fields that appear in the current collection's data structure while Remote Fields are other collection's data fields that are linked to the current Collection through a Link Widget, a Linked Grid widget, or a Combo Box Widget that gets its values using Lookup Options. If the current Collection does not have a linked relationship with another Collection, the only collection that will appear will be the current collection.

Selecting a Field in the Expression Builder

1. While looking at the Expression Builder click on the Field button.
   
2. The Select a Field window will appear, click on the Collection drop down menu. The FORM collection will list the data structure for the current collection, other collections that appear on this list are linked collections. The field linking the current collection to the remote collection will be listed with the linked collection's name in parentheses.
   
3. Click on a field's name to select it, the Select a Field window will close. The field will now appear in the Value or condition area of the Expression Builder, if you mouse over the field's name a bubble will appear defining the location of the field that is used in the expression.