BAKERSFIELD, Calif. -- Many of us enjoy a warm fire on a cold winter day, but not too many understand that there are illegal types of firewood.

According to the Department Of Agriculture and Measurements Standards, firewood has its own special unit of measurement called a "cord." A cord of wood must equal 128 cubic feet, an amount equal to to 4 feet high, 4 feet wide and 8 feet long. With this measurement, there's only one proper way to determine if the wood is in fact a cord and that's to measure it when it's "well-stowed and stacked."

Terms to look for when picking out firewood are rack, rick, tier, pile or truck load -- those are illegal to use in the sale of firewood.

Buyers are encouraged to be wary of exactly how much they are getting when a seller says that there's a cord of a certain type of wood. Also, by law, all the wood sold in a cord must be of the same type (oak, pine, fir, etc.), according to the DOAAMS.

Also, sellers by law are to give buyers a receipt for their purchases in writing that contains the sellers' information, including name and address.