Comment by atrust

I loved Perl 5. Now when Perl 6 is out, I'm a bit confused about versioning. As far as I understand, perl 6 files are of .pl6 extension. Why would that be different from regular .pl, giving that it's just a new version of a language? I mean, I have never seen things like .js5, .php6, etc. Next, is `use v6;` mandatory? Quite confusing. Am I allowed to do `use v2;`?