This should help:
https://panerai.watchlounge.com/watc...ina-automatic/
The xx/ 1000 goes by letter reference.
seems like its a L,P,Q, or R based on my quick search.
The letter will correspond to a year.... then the xx/ 1000 will be the number it was out of the limited run that year.
Panerai then has special "limited editions" that are more special than this "normal" limited run.
But either way, great watch.... not too common. Welcome to the Pam-ily.