How are anonymous participants counted in the attendee report?

[scj13]

When we host a webinar, we look at the attendee report to see how many people joined. I noticed, though, that this report only includes people by name and email. We do allow people to join without signing in, and one participant during the webinar was listed only as "anonymous". Does anyone know if these anonymous attendees still counted in the report? Mostly curious if the attendee report is a true count of all the people who attended.