How do I set the Document Format in OIR rule?

I've made a custom OIR rule for a library that sets several attributes, but when I use it to upload files from the web, none of the files get a "Document Format", and therefore can't be added to a workspace(they should be cad files).  Does anyone know of a specific attrValue/AttrContraint set that will let the format be detected again?

Thanks

I'm using PDMLink 10.1