What do the numbers and letters on an ATV or motorcycle battery mean?

On a motorcycle battery, the first letters usually refer to the manufacturer type. The number is the amount of actual voltage, and the last letters are for the position of the terminals. Therefor, a battery such as a YTX12-BS means it's a YUASA brand battery with 12 volts of power and the BS means that the terminals are on top with holes on both sides (top and front) for the screws.