### Summary

- When expanded to a 2D treemenu, multiple hierarchies may have multiple links to represent nodes and terms.
- When a term or node is paged, various treemenu functions, will not know how to react. These functions must be abandoned, or special measures taken.

### Description

Here is a very simple multiple parent hierarchy,

    +--------------------------- tid 9 ----- +
    voc3 +----- tid 5 --- tid 7 ----- node 34

But a 2D screen menu is not a multiple parent hierarchy, it's a single parent hierarchy. The conventional approach is to expand like this,

    +------------------------ tid 9 ----- node 34
    voc3 +----- tid 5 --- tid 7 ----- node 34

(Note that we have abandoned a possibility. Instead of multiplying nodes and keeping the parent structure, we could keep the nodes and shred the parent structure. However, most people regard the parent structure as more important than the nodes themselves. Hence ...bloggers?)

What happens when page q=node/34 is called?

Well? Drupal gets it's information from the URL. If the menu is in a block, it has absolutely no idea what to do next. If expanding, which path does it expand down?

    voc3 >> tid 9 >> node 34

or

    voc 3 >> tid 5 >> tid 7 >> node 34

And which path is the breadcrumb? If the menu doesn't know where to go, neither do the breadcrumbs.

Taxonomy Treemenu has offered several answers to this ambiguity in the past, and probably will in the future. You may want to look at our notes on menu prefixes and multiple breadcrumbs.