What is a Bill of Quantities (BoQ) & a Bill Extract?

Bill of Quantities (BoQ): According to www.ask.com, “A Bill of quantities is a list of numbered items, each of which describes the work to be done in a civil engineering or a building contract. Each item shows the capacity of work involved. The bill is issued to tenderers, who return it with a price opposing each item.”

Bill Extract: The portion/s of a BoQ which relates to the supplier/vendor/sub-contractors’ trades, i.e. the specific trade/s that a supplier/vendor/sub-contractor does.