Opportunities for short-term investment have been proliferating rapidly over the past several years, resulting in a confusion of products that makes selecting among them as bewildering as choosing a microcomputer system. The one stock market professionals like best is index futures, a commodity that traders understand far better than they do soybeans. This slender volume, by a stockbroker who in 1981 wrote the prescient How to Profit from the Coming Bull Market, skims the surface of the subject, making definitions clear enough but unfortunately coming up short in any insight into the insider techniques that make this one of the Street's highest-leveraged, fastest-paced games.