A product that claims openness and conformance to standards that have no enforceable meaning.
Mini-AntiPattern
A wolf ticket, in the original slang, is an event pass sold by a scalper with no authority to sell it. The AntiPattern version: a product that claims openness and conformance to a standard that carries no enforceable meaning.
Only 6 percent of information-systems standards have real test suites, and most of those are for programming-language compilers. Everything else runs on the honor system. A product ships with a proprietary interface that drifts from the published standard, and the buyer only finds out at integration time, when "open" and "portable" turn out to have meant nothing contractual.
Don't take a standards claim on faith. Run a spike: get two implementations talking to each other before the purchase order is signed, not after. Standards do lower migration cost and improve stability when they're actually enforced. They do nothing for you when they aren't.