Source

File: wp-admin/includes/meta-boxes.php

function link_target_meta_box( $link ) {

	?>
<fieldset><legend class="screen-reader-text"><span><?php _e( 'Target' ); ?></span></legend>
<p><label for="link_target_blank" class="selectit">
<input id="link_target_blank" type="radio" name="link_target" value="_blank" <?php echo ( isset( $link->link_target ) && ( '_blank' === $link->link_target ) ? 'checked="checked"' : '' ); ?> />
	<?php _e( '<code>_blank</code> &mdash; new window or tab.' ); ?></label></p>
<p><label for="link_target_top" class="selectit">
<input id="link_target_top" type="radio" name="link_target" value="_top" <?php echo ( isset( $link->link_target ) && ( '_top' === $link->link_target ) ? 'checked="checked"' : '' ); ?> />
	<?php _e( '<code>_top</code> &mdash; current window or tab, with no frames.' ); ?></label></p>
<p><label for="link_target_none" class="selectit">
<input id="link_target_none" type="radio" name="link_target" value="" <?php echo ( isset( $link->link_target ) && ( '' === $link->link_target ) ? 'checked="checked"' : '' ); ?> />
	<?php _e( '<code>_none</code> &mdash; same window or tab.' ); ?></label></p>
</fieldset>
<p><?php _e( 'Choose the target frame for your link.' ); ?></p>
	<?php
}