posted 14 years ago
The difference in the article's terminology is one of navigability--but as far as I know Kengkaj is correct, this isn't an official UML term.
Using the article's terminology an "association" is bi-directional, meaning you can get from one class to another. A "directed association", in the article's terminology, means that the association isn't "reversible". I've also seen navigability enforced with the addition of an "X" on the other (non-arrow) end of the connector.
One example might look like this (from UML 2.0 Distilled):This would mean that you couldn't get a cursor's window from the cursor instance.