Metalevel (or reflective) knowledge is knowledge about other knowledge--like domain knowledge and problem-solving knowledge. In other words, metalevel knowledge has models about concepts, relations,tasks and methods. These models are formed by metalevel concepts, metalevel relations, metalevel tasks, and metalevel methods. Moreover, metalevel knowledge also includes preferences to model decision making about sets of alternatives present in domain knowledge and problem solving knowledge. For instance, metalevel knowledge models criteria for preferring some methods over other methods for a task in a specific situation. An example of metalevel task is to choose a method for a given task. An example of metalevel method is one that--for a specific situation--searches possible methods for a task, selects some methods as suitable alternatives, and finally sorts them using a set of preferences.