Excellent post by tye

I almost always use an ampersand because I think of it as another "type" delmiter - scalars start with a dollar sign, arrays with an "at", hashes with a percent, typeglob with a star, and subroutine with an ampersand. Why file handles did not get their own little symbol is still a mystery. :)

I also believe that it is required when you undef a subroutine, FWIW