Here begins the lesson on Embrace, Extend and Extinguish (EEE). Classically, this technique is used to perpetuate vendor lock-in by introducing small incompatibilities into a standard interface, in order to prevent effective interoperability, or (shudder) even substitutability of competing products based on that interface. This EEE strategy has worked well so far for Microsoft, with the web browser, with Java, with Kerberos, etc. It is interesting to note that this technique can work equally well with Microsoft's own standards, like OOXML.