It is possible, while filling out a form, to select which element(s) you want to display in your external lists. This option works whether it is a hierarchical, referential, referential-hierarchical or a code list.
Add the element that will be used as a filter for your external list; if you wish to filter your list with a field in your form. This element can be an ' Input field', a ' list'(or its label or code), a ' slider', a ' checkbox', a ' counter', a ' choice', a ' reference', a ' barcode', a ' NFC tag' a ' Calculation' element.
Add a List element you will link with your external list. In order to do so, click on the green pencil to access the settings of this element. Then, in the scroll bar, select your list.
Click on the Advanced tab. First of all, choose if you want to filter:
By one of the references of your list (either referential or referential-hierarchical list)
By one of the hierarchies or your list (either referential or referential-hierarchical list)
Using codes of your list.
Select the mathematical symbol that you wish to use.
Finally, select the element that will be used as a filter.
Then, you will be able to select what will be displayed on your list according to what will be put in your element (all types of elements we listed in the second bullet point), a fixed value or a customizable user field.