Final answer:
A UI policy action can change various attributes of a field on a form, such as visibility, read-only state, mandatory requirement, and default value.
Step-by-step explanation:
A UI policy action in a form can change various attributes of a field, such as its visibility, read-only state, mandatory requirement, and default value.
For example, a UI policy action can hide a field if certain conditions are met, making it invisible to the user. It can also make a field read-only, preventing the user from modifying its value. Furthermore, a UI policy action can mark a field as mandatory, requiring the user to fill it in before submitting the form. Lastly, it can set a default value for a field, which will be displayed initially but can still be modified by the user.