What is Altbier?

[SnickASaurusRex]

I am having trouble pinpointing this style.

 

[EvilTOJ]

Here's what I found from the BJCP guide; It's an ale that is lagered after fermentation.

Description: Altbier or "old beer" from the city of Dusseldorf. Uses a top fermenting ale yeast at ale temperature, but then is cold-aged. "Old" method before lagers became popular.

Profile: Light to medium body. Dry, clean and bittersweet. Low hop flavor and aroma. Medium bitterness. Some fruitiness. Medium to high maltiness. Color is bronze to brown. Low diacetyl. Moderate-high carbonation.

Ingredients: German Munich malt with small amounts of crystal, chocolate or black malt. Occasionally some wheat. Spalt hops or other noble German hop. High attenuation ale yeast, but cold aged.

Examples: Schumacher, Im Fuchshen, Zum Schlussel, Diebels Alt, Frankenheim Alt, Widmer Ur-Alt

 

[SnickASaurusRex]

I assume that cold aging is in bulk. Can it be cold aged in bottles.