This tells UMS to maintain groups that are not coming from the administrative system.
Implicit group memberships
inLogic recommends using this feature in UMS.
This will add the security group of the template to the group entered here.This group will not show up on the users Member Of tab but instead it will show on the security groups Member Of tab.
It will also add the distribution group if the Implicit group is mail enabled.
This means the user will be a member of both groups since it is member of a group that is a member of another group.
Explicit group memberships
This will add the user directly to the group in Active Directory and this group will then show on the users Member Of tab.
UMS will not remove users from this group it will only add missing users that is known to UMS. This is normally a manual group which means UMS can not remove users that are in the group and UMS doesn't know.
If you want groups that are explicit and fully maintained automatically then use Custom SQL Commands#Add users to groups