1. In a computing environment, a data structure for indexing identifiers, wherein the identifiers correspond to parameter patterns, and wherein the presence of an identifier in the data structure indicates that the corresponding parameter pattern may be present in a set of parameter patterns, and wherein absence of the indicator in the data structure can be used to indicate that the corresponding parameter pattern is not present in the set of parameter patterns, the data structure comprising: a first field, wherein the first field comprises a first plurality of binary bits, each binary bit corresponding to a possible identifier corresponding to a parameter pattern from among a first set of parameter patterns, and wherein when the bit is set, the identifier is included in the first field; and one or more additional fields hierarchically below the first data field, wherein each of the additional fields comprises at least one of identifiers for a subset of the first set of parameter patterns represented by identifiers in the first field, identifiers for a parameter pattern related to one or more of the parameter patterns in the first set of parameter patterns or a subset of parameter patterns or related parameter patterns represented by one of the other one or more additional fields hierarchically above the field including the identifiers, wherein the absence of an identifier corresponding to a parameter pattern for a particular field indicates that the parameter pattern is not represented by an indicator in fields hierarchically below the field irrespective of the presence of identifiers corresponding to the parameter pattern being present fields hierarchically above the field not including an identifier corresponding to the parameter pattern, and wherein the absence of an identifier corresponding to a parameter pattern at any level in all of the hierarchical threads indicates that the parameter pattern is not present in the set of parameter patterns.