Why Is Norco Referred As Hydrocodone Instead Of Hydroxycodone?

I have had a running debate with several pain clinic physicians regarding the pain medication "Norco". When my pain physician first started me on Norco in 1996/7 he told me that it was a new type of narcotic analgesic called Hydroxycodone and that it contained less acetaminophen than Percocet, Lortabs, Vicodin, etc. (325mgs vs 500mgs). I was having trouble taking all of the other narcotic pain medications for serious/chronic back pain. However, the Norco was different. It did not leave me feeling "strung-out", "drugged-out" or "high". It simply got rid of the pain or at least reduced it to about 80% of what it had been so that I could do my job. However, around 2004 or 2005, the pharmacies changed the ingredient "name" to Hydrocodone and Norco was bunched together with all of the other narcotic analgesics INCLUDING Vicodin, Lortabs, etc., all being called hydrocodnes. Yet, when I was given anything BUT Norco, I would itch, sweat, and develop a rash. This has been really odd. I do know that when I had spoken with many other pain patients over the years who had been tried on Norco, they hated it, stating that it just wasn't potent enough for them and they preferred the Lortabs, Vicodin, Percocet, etc. Yet, it worked for me. Which brings the question back around full circle. Norco is made using Hydroxycodone and the other pain medications are made using Hydrocodone, Oxycodone, Hydromorphones, etc. So, why is Norco referred to as Hydrocodone when it really isn't? I have a PhD in anesthesiology and neuro-chemical pharmacology and have done my research yet many pain physicians seem clueless. What are your thoughts? Thank you.