Reading through 2.3.5 (Lists and Garbage Collection), it looks like it's describing a tree where the leaf nodes also contain references to the root of the next

Reading through 2.3.5 (Lists and Garbage Collection), it looks like it's describing a tree where the leaf nodes also contain references to the root of the next tree. This wouldn't work as a copy-on-write tree, as the root node is changed every write. Copy-on-write behavior requires very strict trees, and this gets in the way of adding extra structures for traversal.