Method chaining eliminates an extra variable for each intermediate step. This feature permits higher throughput than encryption algorithms, like CBC, which use chaining modes. There are mainly two modes for an inference engine&colon; forward chaining and backward chaining. Players must master techniques such as blocking, counter-attacking, and chaining attacks together into "combos". With small record sizes, these factors can yield better performance than chaining, particularly for lookups. In addition, some rules engines support backward chaining. It is equivalent to the chaining together of multiple simple DMA requests. Both chaining and cascading come from the Smalltalk language. Early inference engines focused primarily on forward chaining. It shares characteristics with cognitive psychology's dissociation logic and philosophy's forward chaining. This could be especially powerful with backward chaining. KEE had a complete rule engine with forward and backward chaining. Larger Multiplexers can be constructed by using smaller multiplexers by chaining them together. Backward chaining is a bit less straight forward. The opposite of forward chaining is backward chaining.