Past Perfect VS Past Simple in the context of previous experience

I have three extracts:

1st:

A: Do you know this man?

B: Yes, I had met him before war, but I haven't seen him since that time.

2nd:

A: Is he a student?

B: Yes, he studies at our university. He worked at our university. He worked at our factory before he entered the university. He isn't working any longer.

3rd:

A: Where does he work?

B: He isn't working now. He's a student. He worked at our factory before he entered the university.

Once I posted the first sentences having asked about the acceptability of using Past Perfect in that context. The answer was that "war" isn't a "reference time", so that I had to use Past Simple in the examples 2 and 3, meaning that "working" was a habitual action that is no longer valid.

But what does "reference time" mean?

Answer

When you wrote "before" you were describing a point in time, but following it with "war" is incorrect.

You reference a time (before) but are unclear about the specific time.

Writing "war" does not indicate a time.

The correct way to write it would have been:

B: Yes, I met him before the war, but I haven't seen him since that time.

If you want to get really specific:

B: Yes, I met him before WWII.
B: Yes, I met him before the war in (place name).
B Yes, I met him before the war of 1812.

B: Yes, I met him before the war started.
B: Yes, I met him before the war ended.