When designing an AF Element template, there is a checkbox titled "Allow Extensions". This checkbox enables or disables any user from creating additional AF attributes in any AF element that is built using that template. The default setting is unchecked (i.e.: don't allow extensions). This means that all elements based on this AF Element Template will have the same exact set of AF Attributes.
It should be noted that the "Allow Extensions" setting does not affect AF Analytics of Notifications associated with an AF Element. Even if a template does not allow additional attributes, it will allow the creation of AF Analytics and/or Notifications. The "Allow Extensions" setting also does not restrict derived AF Element templates (i.e.: AF Element templates that inherit from another AF Element template) from adding AF attributes.