The present invention is directed to thermo-expandable microspheres and to the expanded microballoons, microcellular foam or foamed composite material that results upon heating the microspheres. A checker program checks the initial test definition for compatibility with each of at least two different testers. The subject of the test must either recognize a semantic or symbolic association between two or more objects, or isolate an object that does not belong with the others, indicating their selection by typing the name of the object with their keyboard. Lack of spatial locality results in a high probability that a miss will be incurred at each cache in the memory hierarchy. At least one of the types is an immutable type, and the immutable type has at least one immutable field. This method makes the sub-service procedures of each service user independent from each other, with high efficiency, less workload, and more flexibility and convenience.