Welcome Mikael,
you are not alone from Denmark here on this forum. Peter and Jan are also regulars here ( both Dane's ) and i'm an Australian living i Copenhagen ( i speak Danish )
May i ask is the dial on your watch a glow in the dark yellow? The letter designation after the serial number could well note the colour of the dial. In Italian N = Negro (black) and i'm guessing here but the L could = Luminous (glow in the dark) such as my 980.031 - here's a couple of photo's



Hope this helps you - Darren

-
-
-
-
-: Hi !

: I am new to this forum. However, I hope that some of you experts
: can help me date - approx. - the Tag Heuer Profesional 1000
: METERS QUARTZ ref. no. 980.023L I just bought.

: The case is similar to the Spirotechnique one, and I was told it
: was probably manufactured in 1986-1987. I can't find the
: serialnumber on the case, but I trust/hope that the L in
: conjunction with the ref. no. "says something" ?

: The "other" 980.023's I have heard of/seen all cary an N
: after the ref. no., so .....

: Rgds
: Mikael