OPML is an XML format for outlines (defined as a tree where each node contains a set of named attributes with string values). The following file allows WordPress to import links from other websites as long as they're in OPML format, but visiting this file also discloses the version information (in between HTML comment tags) as shown in the following screenshot:
/wp-links-opml.php
This can be seen in the following screenshot:
Next, we will look at advanced fingerprinting.