As of Now the Rule CONDITIONS seems only available on Fields that are visibly displayed on the Form
....it is not listing ALL OTHER available Criterias field/column that already exist in the table but are not displayed (yet) on the Form.
There is many cases where it would be practical to set a condition on fields that are not showing on the Form but do exist on the Form based Table.
I.E. in the sample show below,
One could set a condition upon the content of field GRS. (in the Grey left Panel)
... and display a resulting ICON in an "Image column".
n this way, the form would only need to display 1 column : "icon column"
As it is now set:
...it is necessary to show BOTH, the Criteria column + the Icon column, doubling the number of column to display as a result. which is not always required in all case...