IEEE 11073 Packages and Abstract Base Classes

The Packages

As is typical in a logical model other than a very small one, the objects are grouped into packages of objects that are closely connected logically. Examples in the DIM are the System package, and the Medical package (the DIM contains other packages for functions such as alerts, and supervisory control, that are not within the scope of this Implementation Guide).

The System package covers instances of hardware components of the medical device, including the Medical Device System (MDS) object which stands for the entire device and has attributes representing such whole-device characteristics as manufacturer, model and serial number. The MDS package also may contain Log, Battery, and Clock objects. In cases where an MDS proxies information from another whole device, as happens when, for example, a physiological monitor receives information from another device such as a ventilator, the MDS object can contain another MDS object.

The Medical package contains objects representing subsystems of the whole device (Virtual Medical Device objects or VMDs), and within a VMD, (optionally, as needed) Channel objects. The Medical package also contains the hierarchy of objects representing different kinds of measurements and observations such as Numeric, Enumeration, and Real-Time Sample Array.

Abstract base classes - abstract the common attributes of a hierarchy of objects

These are abstract classes that are not implemented, but from which implementable concrete classes can be derived. The abstract classes contain attributes that are shared by the objects in the inheritance tree, for example identity data - such as unique handles for all the objects in a potentially complex hierarchy.

The Virtual Medical System

Superclass of the Medical Device System. Provides for consistent naming and identification of System package objects.

The Virtual Medical Object

Superclass of Medical Package objects such as Virtual Medical Device and Channel.

The Metric

Superclass of various metric types, including numerics, enumerations, and real-time sample arrays


Attributes of concrete objects may be inherited from the above base classes or particular to the concrete objects. Some are mandatory but many are optional. The most commonly used are present in the FHIR resources DeviceComponent and DeviceMetric. Others may be represented in FHIR extensions.

It is important to note that many attribute values remain the same for many successive observations and the corresponding FHIR resouces are sent or updated only on change.

The 11073 DIM distinguishes Static and Dynamic Attribute Groups, reflecting attributes with values that are typically long term characteristics of the corresponding physical instrument or part of the instrument versus others that are more likely to change over a shorter period of medical care.