As a supplement to my entry on the main supplier for trading jackets, I thought it'd be good to note that Lazare Printing is the main supplier for trading cards for pit traders in Chicago. To order some, contact them at the following link:
http://www.lazareprinting.com/cards.htm
A quick explaination on how the above card functions: At the top is the traders badge (referred to as "mnemonic" at LIFFE) of "JD" and below is his name "John Doe" and then the account number of "0000." The left two columns are where the trader writes the quantity of contracts that are bought or sold. It's listed as "Cars Bought" and "Cars Sold" which originated from grain trading and each contract was referred to as a car because the quantity of one contract was roughly the amount of grain held in one railcar. The "MO" column is where months are listed via their designated month code letter and the 12 months starting with January are F, G, H, J, K, M, N, Q, U, V, X, Z. The code for the contract is written above the month code, for instance ED for eurodollars. If the transaction is part of a spread trade, there is a diagonal slash through the "MO" column and an S is written below the slash to designate that it was one leg in a spread. "Opposite" is where a trader lists the one, two, three, or four letter badge of the person they traded with and below the badge is the three digit number of the clearing firm which processes and guarantees the trade. "Price" is obviously the price at which it was traded. "BKT" is the code letter for the 15 minute time bracket that the trade was done in. Each exchange has a different trading card and the above example is the style at the CME.
Also, generally on top of each card is a thin carbon duplicate which is torn off and kept by the trader or their trade checker (who confirms trades in the pit w/the counterparty). The card itself goes to the backoffice to get the information punched in and is kept by the clearing firm. After the FBI sting in 1989, it became required that only ink can be used to write on cards and no pencils.