1. A system for user customization of clinical data objects using a clinical modeling language, the system comprising: a processor and a memory to implement: a constraint definition language processor to define a detailed clinical model to express a clinical concept as a standardized and reusable set of clinical knowledge, the constraint definition language processor using a compiled, context-free constraint definition language to define the detailed clinical model as a compiled object, wherein compiling the detailed clinical model into a compiled object validates the detailed clinical model for correctness and consistency, the constraint definition language processor providing the compiled object as content for at least one of a clinical content database and a clinical information system, wherein content represents one or more parameters to instruct a clinical application, wherein the detailed clinical model defines an information model representing one or more instances of clinical information and a logical model representing an implementation of this information model, wherein the logical model represents clinical data using a two-layer data modeling approach in which a structure of a clinical data object is separated from a definition of information contained within the clinical data object, the logical model (i) defining information in the detailed clinical model as a set of constraints progressively limiting allowable data values in the detailed clinical model until a specific clinical data item is defined and (ii) defining relationships among information in the detailed clinical model, wherein the constraint definition language processor authorizes the detailed clinical model including the information model and the logical model and wherein the constraint definition language processor validates the detailed clinical model for correctness and consistency and compiles the detailed clinical model into the compiled object to instruct the clinical application regarding execution and consumption of data, the detailed clinical model extensible to allow a new detailed clinical model to be defined by a content author and an attribute to be added to an existing detailed clinical model to change behavior of the clinical application without requiring corresponding changes to the clinical application or underlying database structures.