In a merge:
What this means:
If A is renamed to B in the trunk and
A is renamed to B in the branch then
trunk.B becomes the "ancestor" of branch.B
If A is renamed to B in the trunk and
A is still called A in the branch then
branch.A is renamed branch.B
trunk.B becomes the "ancestor" of branch.B
If A is renamed to B in the trunk and
A is renamed to C in the branch then
trunk.B becomes the "ancestor" of branch.
In a join:
The only possible ambiguity arises from differing renames (the last case above). When a join occurs in this case, trunk.n.B will be renamed to Trunk.n+1.C.