In Enterprise Architect, internal requirements are requirements that are specific to one element. For example, an internal requirement to enable the user to log in to the system could be defined for the Login Use Case. This is a requirement of the Use Case - an action it is responsible for carrying out - and it applies only to this Use Case.
Internal requirements form the functional requirements of the system to be built. The meaning of the requirement can vary depending on which element is the host; for example, a business process requirement might mean something different to a Use Case requirement, which again might mean something different to a Class requirement.
Internal Requirements are defined on the 'Requirements' page of the Responsibilities window. The significant parameters (or, in Requirement Management terms, attributes) are the Type, Status, Difficulty and Priority. Whilst you can provide a detailed description of the requirement in the 'Notes' field, there is more scope in the name ('Requirement' field) to define the nature of the responsibility. An additional field, 'Stability', indicates the probability of the requirement changing; high stability means a low probability of change.
The example Use Case also has connections to two external Requirement elements, which are system functions that the Use Case implements either in full or in part. You can convert an internal requirement into an external Requirement element.
You can also create internal requirements for an element using an instance of the Responsibilities window within the element 'Properties' dialog. A requirement created in the window displays in the 'Properties' dialog, and vice versa.