Spread: (1) In a quotation, the difference between the bid and the ask prices of a futures contract. (iasg.com)
This variation margin is based upon the opposed changes in prices of the futures contracts that are hold by the clearing members who make payments in their corresponding clearing houses. (forex21.com)
But there's a nice set of resources and tools specific to futures, including the «Vertigo Ladder,» a color - schemed chart that shows real - time pricing, depth of market and volume by price of a futures contract. (creditdonkey.com)