Gucci vintage bag numbered. What are these numbers?

[Chiara]

Hello everyone I'm Chiara, I am new in this wonderful forum. Congratulations to all. I found this bag gucci hard leather, the inside there are these numbers.
Mod. Brev. No. 81383

Can you tell me what it is?

 

[Joji Furukawa]

Mod. Brev. is short for modello brevettato which means patent number in Italian. I thought maybe it was short for the French brevet but seeing as the bag is Italian, I searched for the Italian translation instead. Nice bag!!