Regarding /etc/login.conf

From: Inquiry (openbsd_inquiry_at_yahoo.com)
Date: 06/24/05 

Date: 23 Jun 2005 22:41:09 -0700

Can you tell me what the "tc" in /etc/login.conf stands for in the
following. I looked at the man login.conf docs but found nothing with
regard to tc.
  
 default:\
     ...
     :tc=auth-defaults:\
     ...