Currently, when configuring a Business Rule, a multi-select option set field is not available within the list of fields for a Condition. A practical need is to Show/Hide the field on a form.

First Part:
The idea would be to allow a Condition using the "Contains" or "Equals" filter. As multiple values can be chosen in a multi-select field, the "Contains" or "Equals" would allow for choosing specific criteria.

If "Equals" is chosen, then a window would appear with the list of values in the option set. One or more values could be chosen.

Second Part:
The idea would be to allow a Condition using the "Contains Data" or "Does Not Contain Data". This would allow for checking if values exist.