At C1 level, you should be able to understand a wide range of demanding longer clauses and recognize implicit meaning. That means messages which are not specifically stated but hinted at, suggested. You're able to speak fluently without lots of pausing or having to think too much about what it is you're going to say next. And finally, someone at C1 level should be can produce clear, well-structured detailed text on complex subjects showing controlled use of organizational patterns, connectors and cohesive devices.