=over

=item Handle->output_field_separator( EXPR )

=item $OUTPUT_FIELD_SEPARATOR

=item $OFS

=item $,
X<$,> X<$OFS> X<$OUTPUT_FIELD_SEPARATOR>

The output field separator for the print operator. If defined, this
value is printed between each of print's arguments. Default is C<undef>.

Mnemonic: what is printed when there is a "," in your print statement.

=back