These low-level or primitive steps provide the flexibility to compose different types of guidelines such as those listed earlier. We hypothesize that modeling guidelines with primitive steps is cognitively difficult and may cause incorrect representation of a guideline. In addition, specifying guidelines using low-level steps can lead to large and visually complex flowchart representations. We have introduced a new construct called macro into GLIF for representation of domain-level concepts. Subclasses of macro represent different types of domain-level concepts and contain attributes particular to that concept.
Macros enable declarative specification of a procedural pattern in the domain concept.
The pattern is then realized by a set of primitive GLIF steps. The definition of the macro and its subclasses include the information necessary to map the macros to the corresponding pattern of primitive GLIF steps. The mapping also enables sharing of guidelines that contain macros. Sites and software tools that recognize the macro subclass can take advantage of the domain-level representation for authoring, visualization, and execution. PDF readers are available .