Be able to filter out drop down menu items based on form data.
For example, you can create a category node with subcategories as child nodes in jcr.
Using this king of information, it is possible to use the path attribute to get the list of categories in a dropdown select field. However, it is very common to have another dropdown with only the subcategory items that are relevant to the category dropdown selection.
Same applies to countries and the corresponding cities use case, or product category and correspond products and so on so forth. Currently, this is not supported in Magnolia CMS forms. Each field is not aware of other field selection.