Every application has its own data entry screens, workflow, internal database design, and other nuances, and yet despite this, we talk of semantic interoperability. In order to achieve interoperability, and enable a receiver to aggregate data coming from any of a number of applications, it must be possible to compare data generated on any of these applications. In order to compare data, it helps to imagine a canonical or normal form. If all data, regardless of how it was captured, can be converted into a common form, it becomes possible to compare.
To that end, we differentiate the "model of use" from the "model of meaning", where the former represents the way in which the data was captured, and the latter represents a common representation. All representations recommended in this guide can be converted into a common model of meaning. This common model of meaning can be expressed in a SNOMED CT normal form and/or a RIM Normal Form, thereby enabling data comparisons.