- W (probably in
- X) actually exists, contrary to something someone said in the Chatterbox earlier. It's a filetest operator. It tests to see if a file is writeable by the real UID/GID. Strict enforces good Perl habits, like not using symbolic references and things like that.
If you used that instead of -w, it's a typo. If not, what everyone else said is correct.
To see what kind of options you can feed Perl on the command line or the shebang line, see perlrun. (Note that the version on my box for 5.005_3 doesn't list anything for -W.)