 By “content,” YVH mean a function from indices to truth values, where an “index” is a sequence of parameters. In the simplest case, an index will consist of a single parameter, namely a possible world. In that case, a content will be a function from possible worlds to truth values. In the table used to illustrate the diagonal proposition conception of narrow content in  section 4.4  of this entry, the rows of the table represent contents of this sort.