$ cat test.dat 
foo bar
baz quux
$ perl -wMstrict -M5.010 -ane 'say $F[0]' test.dat 
foo
baz
$ perl -wMstrict -M5.010 -ae 'say $F[0]' test.dat 
Variable "@F" is not imported at -e line 1.
Global symbol "@F" requires explicit package name at -e line 1.
Execution of -e aborted due to compilation errors.