Please note : This help page is not for the latest version of Enterprise Architect. The latest help can be found here.
External requirements are those Requirement elements that have been connected to the current element using a Realization connector. By creating the connector from the element to the Requirement, you create an expectation that the element must implement the requirement as part of the system solution.
In Enterprise Architect, linked Requirement elements are shown in the 'Requirements' tab of the element 'Properties' dialog, but they are marked external and cannot be directly edited (on selection, the property fields are grayed out).
Double-click an external requirement in the list to activate the 'Properties' dialog for the associated Requirement element, where you can view and modify the requirement details and check the requirement hierarchy details.