system.tag.importTags only allowed at the root of a tag provider?

I'm trying to build a comprehensive set of tags from all of our sites, and I've run into a snag.

So far I've parsed out all of the UDTs from across our sites and they are deposited into set of files whose stucture mimics the folder/udt structure at our sites. So, I have a bunch of JSON files that each contain a single UDT. I'm able to import them through the UI, but that would be extremeley cumbersome to try to do with all of our UDTs, so I'm trying to import them while preserving the heirarchy.

If I run:

    ret = system.tag.importTags(filePath, "[corp_iot]", "o") 

it works fine and puts the UDT at the root of the corp_iot tag provider, but if I try to specify a folder it returns an error.

    ret = system.tag.importTags(filePath, "[corp_iot]catalog", "o")    

"Error importing tags: Udt definitions can only be imported in the UDT Definitions tab."

I'd rather not have to construct a JSON file with all the UDTs and the folder structure built in.

What am I missing, or is this just not allowed?

Thanks!

When you say "UDT" I assumed instances, but are you talking about definitions?
For definitions, you need to use the parent folder _types_/
Ie
[corp_iot]_types_/catalogue