terminology - What is 'relevance time'?

What is ‘relevance time’ in the chart below? And would you compare it with ‘narrative time’?

(Angela Downing, English Grammar: A University Course)

(StoneyB's answer in ELL)

Answer

In this Reference Time refers to the time that has already gone by or the past. Narrative time, is the continuation or the present/future events.

The example is nicely given.

Complete Sentence :: I had once vowed never to smoke a cigarette. So many years have passed since I started the habit. Now I think it isn't a sin any longer.

Reference Time

This is an event that has already happened. So in our story, the Reference time is the time that evolved in this part ::

I had once vowed never to smoke a cigarette

During the past, at some point in childhood, or many years ago, I decided never to smoke. That is the reference time. It ends once we leave the past and move to the present.

Narative Time

This is the event that is happening now or in the future. In our sentence that is ::

So many years have passed since I started the habit. Now I think it isn't a sin any longer.

The years have passed (in the past), the present has arrived. Now (again indicates the present), I think it isn't a sin any longer.