The GuideLine Interchange Format (GLIF) is developed by researchers from the InterMed Collaboratory at Columbia University, Harvard University (Brigham and Women's Hospital and Massachusetts General Hospital) and Stanford University to represent clinical practice guidelines.

Object-oriented approach is taken by GLIF. Classes are arranged in a hierarchy. Each class has its own attributes as well as the attributes it inherits from the class above. GLIF classes and attributes are shown in the following figure.

Frames is the most appropriate formalism to represent classes and objects. Attributes of the classes and objects are represented by the slots. Relationship between classes and objects, here in GLIF the hierarchical relationship between classes, can also be represented by slots.