In MS CRM, we can apply security role to entity form. To enable security role for form just click on ‘Enable Security role’ (ref below screenshot), it will give you to select security role from the list.
But what will happen when a user wont have any security role assigned which have access to form. in such condition that user will see only ‘Fallback’ form.
Note: But if user has not access on entity then he wont be able to see any form or data
For each entity, at least one fallback form is available.