Difference between nao and NON in Portuguese

[fish]

What is the difference between Nao and NON  ?-both portuguese words. I know that nao means no or not , but NON is the word used by the Potruguese film director Manoel de Oliveira for his film " no , or the vain glory of command ". I can't find NON in any online dictionaries and don't have a proper Portuguese  (book) dictionary to hand .
I hope someone can help. I know French Spanish and English well and am trying to decipher heavy Portuguese texts with only these other languages .

[jmartin]

NON it's an old version of the word "NÃO". It's not in use anymore, for a longtime. I think Oliveira did use it to reforce the idea that moovie should be seen as sight of the history, where the word "non" did his own evolution as well.

[cbx1100]

I Agree 100%