The above model distinguishes attributes and key-attributes. One important constraint on such key-attributes is monovalence. In the previous releases of ConceptBase it was possible to declare Telos-attributes as instance of the attribute-categories single or necessary, but the constraint ensuring this property could not be formulated in a general manner, because the use of variables as placeholders for Telos-classes e.g in an In-Literal was prohibited. To overcome this restriction, metaformulas have been integrated into the system. An assertion is a metaformula if it contains such a class-variable. The system tries to replace this metaformula by a set of semantic equivalent formulas which contain no class-variables. In previous releases properties as single or necessary had to be ensured ``manually'' by adding a constraint for each such attribute. This job is now performed automatically by the system.