An ensemble consists of individual actors that dynamically collaborate to fulfill a common goal. Successful collaboration requires a certain degree of knowledge and trust regarding the individual characteristics of each ensemble member. As such knowledge or trust cannot be assumed initally, actors rely on credentials issued by mutually trusted third parties. To request, present and verify a particular credential, current approaches expect that the schema, or: syntax, of the credential is agreed upon beforehand. While feasible for many use cases where actors are mostly known beforehand and fulfill fixed roles, this falls short in more dynamic and open world scenarios: In a dynamically formed ensemble, the actors need to understand the semantics of a credentials and its implications for the current situation based on their individual assumptions. In our paper, we suggest a formal framework based on Description Logics, study the Expectation Matching Problem, and sketch an implementation based on Semantic Web technologies.