when going to Administration > Relationships, it looks like you can't
click on the root node of a relationship_type to edit it. But you can
find the edit page for it by clicking on the name of one of its
children, and then in that child's edit view, click on the "hierarchy"
button at the bottom of the page; this shows a different
relationship_type hierarchy browser, which does have the edit links for
the root nodes.
Worse, I managed to break a root node by editing it this way. I set the
"sort_order" to 0 (it was 10), and clicked save, after which that root
(and all its descendents) weren't visible in the Relationships
Administration UI. Looking in the database, it looks like that edit
caused the root node's ca_relationship_types.table_num field to get set
to 0. Manually resetting table_num to the correct value (derived from
the field containing the name 'root_for_159') restored access to the
Relationship category in the UI.
debian wheezy, collectiveaccess git head