To do what exactly?
Accessed via WebDAV? Or via SMB? NFS? AFS?
Probably because you indexed the surrounding folder, presumably 1_tech_materials. To be more precise:
- You index a folder in your Mac file system from DT
- This is represented as a group in DT
- You create a sub-group of this group in DT
- That one becomes a sub-folder of the corresponding folder in the Mac
The question remains: Why are you indexing instead of importing? Indexing is fine if you know about its potential pitfalls. Otherwise, you might well fall into one of these pits. For example, indexed items do not get synchronized to other devices, notably i*OS. Imported items, OTOH, are always synchronized (at least with reliable sync services).