 (There are a number of logical subtleties here that we will not pursue, especially about how to formulate rules, and which rules are consistent. Different formulations of rules vary significantly in logical strength as  well.[4]  See the entry on  axiomatic theories of truth  for more on how consistent forms of capture and release can be formulated in classical logic. In the terminology of Friedman and Sheard (1987), the rule forms of capture and release are called ‘T-Intro’ and ‘T-Elim’, and the conditional forms ‘T-In’ and ‘T-Out’. We prefer the broader terminology, since it highlights a general form of behavior common to a great variety of predicates and operators, e.g., knowledge releases but doesn’t capture; possibility captures but doesn’t release; and so on; and truth is special in doing both.)