The UBB does not support subcategories, you can however use a category of "Operating Systems" and have a forum of "Windows", another of "Linux", etc.

If you want it to show up like at UGN Security you will have to turn category viewing on (CP -> General -> Primary Tab -> Forum Summary Options dropdown, then tick the "Enable Categories" tick and submit).

Additionally, i don't believe there is a mod over at UBBDev for subcategories however it is usually the best place to start for UBB Modifications.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
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