At a given point in the development of a discourse, a referent is accessible in the consciousness of the interlocutors to different extents. This depends on the distance of its last mention and a few other factors. If it is fully accessible, it is fully apt to function as topic in the next utterance; if it is inaccessible, it is inapt for this function.

To these accessibility statuses correspond different means of coding such a referent which may be represented in an accessibility scale. The two scales may be put side by side and then correlate to a significant degree.

The first version of this combination is the Topic continuity scale.