the Tes4Edit Cleaning Guide says:

"Book Jackets Oblivion adds three lights to the BookWarehouse cell. You can safely delete those."

but how? opening the file in tes4dit reveals way too many entries to find those easily :/

I didn't even know there was a Book Warehouse cell in Oblivion.

It wasn't hard to find. Cell Block 9, sub-block 2. Open the temporary tree, scroll down to the end of the list and there's three entries for DODaylight500.

Hardly even worth bothering with either. Stuff in test cells like that won't ever be loaded into memory unless you console into them.

thanks guys