 Formally, character is defined as a function that maps possible contexts of use to contents, and content is defined as a function mapping possible worlds to extensions. Thus, a character is a function that takes as input a context and yields as output a function from possible worlds to extensions. This is a two-dimensional intension, since there are two distinct roles that possibilities play here: as a context of use, and as a circumstance of evaluation (a possible situation relative to which we evaluate whether the relevant object exists or property is instantiated). Contexts of use can be thought of as “centered” worlds: possible worlds with a designated agent and time within that world, which serve to locate a particular situation in which the expression is used. We can then represent a context as an ordered triple, \(\langle w,a,t\rangle\) , of a possible world w, an agent a within that world, and a time t when the agent exists in that  world.[4]  So possible worlds play two distinct roles in Kaplan’s formalism: contexts of use determine which content is expressed and circumstances of evaluation reflect the modal profile of that content. The conventional semantic rules governing an expression like ‘I’ can be easily represented using Kaplan’s 2D framework: in any possible context, \(\langle w,a,t\rangle\), an utterance of ‘I’ rigidly designates the agent of that context, a, in all possible circumstances of evaluation. [See the entry on  indexicals  for a more detailed discussion].