What exactly is "B stock"?

I'm looking at Denon DVD/CD players, and I keep coming across "B stock" merchandise. Would someone who is genuinely knowledgeable about this subject please give a clear, accurate definition of exactly what B stock is, and just how it differs from A stock? (Yes, I have a vague, generalized idea of the difference, but not one I'd want to take to the bank.) Thanks.
B-stock items are items originally purchased new which have been returned to the manufacturer by the buyer. The manufacturer fixes what was wrong and gives the item a general inspection to make sure it is in perfect working order. B-stock items should work like new and should look like new. They are sold for a significantly lower price than a brand new item and often carry a manufacturerer's warranty of shorter duration than a brand new one.
B Stock can be what Jerry says. It can also be much much more.... Usually what Jerry described is sold as "refurbished".

B stock can be brand new gear. They have left over inventory of the old model in the warehouse brand new. They want to clear it out. To help lower the wholesale price they shorten the warranty period. Since they are not selling it with the full new warranty, they slap a B Stock label on it.

B Stock can also be brand new gear that did not pass final inspection because there are slight cosmetic blemishes. Electronically perfect, just might have slight imperfections on the chasis somewhere.

I personally am not afraid to buy B Stock, even refurbushed gear.
I purchased a pair of B stock dynaudio special 25's that were used as the demo pair for Stereophile magazine. They are perfect in every way, I have a full set of measurements for my individual pair of speakers in the June 2005 stereophile, and Dynaudio has honored the full warranty and all other perks of buying "A" stock. Sometimes B stock can be very good buys.
I'm in the middle of a mess with an overseas seller that may be selling "B" stock as new. This is only speculation at this point because the seller is checking with the factory to determine if they made the modification. If we find that they in fact did not do it at the factory and it was not modified by either myself or the original buyer (I purchased on Agon from a very reliable and trustworthy source who did not even open the chassis.) This has the potential to be quite harmful to the credibility of this seller. So does the seller have a duty to disclose that a product was in fact a return, although it may be cosmetically perfect on the exterior?

Survey says ....
The above 2 responses are correct. I purchased a Yamaha DSP-A1 Integrated Amp/Processor 4 years ago as a "B" stock item, brand new. It has been a perfect piece of gear. I don't know why it was designated as such, as I could never find anything wrong with it. I do know this, I paid $650 for a $2799 piece of gear (it was the gold anodized unit with rosewood side-panels)and it had a standard Yamaha warranty except for "cosmetic" issues that might arise. I'd certainly do this again!
In addition to the above, I suspect the occasional tout of B stock may reflect a sales person's effort to circumvent a dealer's factory authorized territory, often citing the opened box or slight blemish in consequence, when in fact the goods are as new.
These days, it could mean anything except for new in box undamaged with valid warantee.
Thanks for the answers; I appreciate them. On the subject of "refurbs," I will add that in the past decade I have bought two "factory refurbished" units from a major manufacturer of electronics with a good reputation, both at reduced prices but from an authorized dealer. I wound up having trouble with both and was left with the clear impression that I'd bought someone else's problem or lemon. I won't be buying "factory refurbished" again, although of course I may have just had bad luck. For whatever it's worth.
Rockvirgo is correct too. I bought a pair of speakers, at a big discount, from a non-local authorized dealer. He said, "they are open box, b-stock, but you won't be able to tell them from new". When I got them, the were brand new, in the factory sealed boxes.
Get2it -

Are you by chance referring to an Esoteric seller? The seller should be aware of what he is selling if he is the first seller.

I will add one more version of "B" stock which has become increasingly popular - show stock. If a manufacturer brings several items to a show to demo as well as pass out to certain folks to 'try' while at the show, when these are returned, they label them 'B' stock.

In addition, as new release are on the horizon, you will see manufacturers reduce prices to dealers (and ultimately to use here on the preowned market) giving them incentives for retail and employee purchases.

Have you ever noticed a certain item just DROPS on the preowned market? In these cases it is likely some type of employee incentive/discount (those that are buying at 30-40% of retail and looking to make 5% immediately even when they are supposed to be holding the item for a year. What this does now is change the supply. More items available, and at a lower price than the rest of the folks selling the same unit. It now forces those selling the same unit to compete, although not necessarily get lower than, the 'cheap sale'. Book values drop and thus the inevitable:

"One just sold for $5,500 will you drop your price $1,800 so I can buy yours?"

Don't be concerned with "B" stock unless it has surely been repaired. I personally am not a fan of repaired goods, unless it was a Mark Levinson or Krell item.