EDIT - The information below was compiled by Davio
TOPICS_T_STATUS
0 - Topic is locked
1 - Topic is open or has been approved by an admin/moderator if moderation is on
2 - Topic has been placed on hold by an admin/moderator
3 - Topic is pending to be deleted.
FORUM_F_STATUS
0 - Forum is locked
1 - Forum is open
CATEGORY_CAT_STATUS
0 - Category is locked
1 - Category is open
REPLY_R_STATUS
1 - Reply has been approved by an admin or moderator and can be viewed by all users
2 - Reply has been put on hold and can only be viewed by an admin or moderator
3 - Reply was rejected by an admin or moderator and will be deleted