Difference between N and L ...

Hello everyone. Often in old references I see after the numbers the letters L or N. For example:

-980.013N
-980.013L

But what is the difference between one and the other? Thanks.

Those are numbers for the old 1000 series.
The N and L were 'version' indicators.

If I remember correctly the 'N' indicated the change to a 'narrow' case (ie flatter than the original), (but there's no guarantee that the 'N' was an abbreviation of 'Narrow') and the 'L' followed the 'N' but I don't know exactly what it indicated (It may even have meant the same thing, but under a revised naming convention).

Ah - ok - I was slightly wrong:
"

• The first execution 1000 Series have a thick case and deep, plain caseback with engraved reference number. Later versions had engraved Heuer logo and reference number. First execustion quartz were powered by an ESA 536.121.
• The second execution quartz is thinner than the first execution and houses an ETA 964.114 movement; there is an "L" suffix added to the reference number.
• The third execution case is identified by a "N" suffix. It is thinner than the second execution case and houses an ETA 955.114 movement.

"

from here :
http://onthedash.com/docs/DiveWatchRefTable.html
(obviously any source should be treated with a certain amount of cross-referencing).

Interesting, I never considered that a number suffix might not refer to anything visible but actually the movement inside!

The 1000 series uses (I think) quite an odd numbering system.