(First_Observed)
Permanent, if From_Group is NULL and this
Gid is not another group's To_Group.
Start, if otherwise.
Last_Reg_Census (Last_Reg_Census)
Name (Name)
Gid (Gid)
(First_Observed)
GROUPS
Permanent (Permanent)
Cease_to_Exist (Cease_to_Exist)
From_Group (From_Group)
(Impermanent)
(First_Study_Grp_Census)
Study_Grp (Study_Grp)
To_Group (To_Group)
NULL, if Study_Grp is NULL.
Permanent, if no From_Group
and this Gid is not another
group's To_Group.
Group's earliest CENSUS.Date
where Cen =TRUE, if otherwise..
(First_Study_Grp_Census)
Grp
Cen
Date
CENSUS
(Impermanent)
Earliest Start of all the group's
descendant groups; those with
From_Group = the group's Start
OR those with Gid = the group's
To_Group.
NULL, if no such groups found.
From_Group
Start
GROUPS (DESCGROUPS_START)
Gid