The core entity in the ABE is MetricDefinition. It provides basic facts that define or specify what a metric is, such as the name, description, and so forth. Any entity in the SID can be measured. The association between MetricDefinition and RootEntityType provides this capability.  Instances of RootEntityType represent all the entities in the SID model. The *-* association between these two entities allows the same definition to be used to measure any number of entities in the SID model and for a SID entity to be measured by any number of definitions.<br/>The definition of a metric can also be categorized, such as a business metric, a fraud metric, a revenue assurance metric. The association to MetricDefintionCategory allows many different categorizations of a MetricDefinition via the *-* association. The recursive association on MetricDefinition enables categories to be divided into sub-categories as needed, such as a revenue sub-category of a business metric or a profitability category of a business metric. <br/>MetDefBusinessValue enables multiple relative business values to be associated to the MetricDefinition, such as revenue benefit, cost benefit, efficiency, customer experience, time to market, and so forth.<br/>