What does the loggedin column of vBulletins session table mean?

In vBulletin 4.2 the session table has a column loggedin. Since VB doesn't seem to have a official database documentation, I want to know what exactly it means because the column it's a SMALLINT instead of simple boolean value.

My previous reverse engineering: 0 means not logged in. 1 and 2 is used for logged in users, but I can't see what's the difference. I have both regular user session and admin panel sessions with loggedin=2.

Tried to get more information by running grep on vBulletins php files, ~~without luck~~ .

So my concrete questions are:

What is the difference between sessions with 1 and 2?
Are there more states than 0, 1 and 2?
Do they even matter when vBulletin's code doesn't seem to use them?

Solution

I learned that my filter to *.php files broke greps recursive scanning method. The correct command to scan all php files for 'loggedin' (in quotes since vB use them this way on it's $vbulletin->session object) is:

grep -rn --include \*.php "'loggedin'" .

This gave a few results. Most interesting:

./includes/functions.php:7558:                  $vbulletin->session->set('loggedin', 2);

Opening functions.php we see the call and we can feel lucky that at least in the code vB developers to decide that a comment would be usefull:

if ($vbulletin->session->vars['loggedin'] == 1 AND !$vbulletin->session->created)
{
      # If loggedin = 1, this is out first page view after a login so change value to 2 to signify we are past the first page view
      # We do a DST update check if loggedin = 1
      $vbulletin->session->set('loggedin', 2);
      // ...
}

So we can say that 1/2 doesn't gave information about the type of session. It could be a regular user or also admin session. Altough loggedin indicates if the user already viewed some other pages or not, whyever vB devs need to devide this.