I was worried that the documentation was trying to say that if it looked like an absolute path on a local machine it might not look absolute on another machine.

You don't need to worry, unless those two machines are on different OSes, e.g. Windows vs. *NIX, since File::Spec loads the appropriate OS-specific module under the hood. On a *NIX system, it will say C:\\foo isn't absolute (on a Windows system, it'll still say /foo is absolute).