The contact matrix allows administrators to determine which users appear in which other users' contact lists. As with search permissions, this is done using a matrix.
|First, the source and target must be selected.|
Now the contact matrix can be edited. The x and y axes have organisations / groups / users on them, and the squares in between show their relationship.
Checking the "Make all possible connections" box connects all the users represented in the matrix.
The "Only pending invitations" box hides everything except pending invitations when it is checked.