Results of contemporary research in discourse of type and typology indicate that there are number of conflicts in definition, nature and concept of type and typology in architecture as a unique abstract image presenting a group of buildings. This is an exaggerated statement in the field of architecture, type represents a group of architectural components that has been identified to follow a certain mechanism in the course of collecting and classifying it. Type provides facilities to preserve and recall experiences as a concept and tools, linking the past to the future. Type, therefore, can be seen as the faculty for retaining and recalling architectural experience. But, according to this definition, some experts consider the physical aspects of types, while others study metaphysical and intuitive features of it. For example, In Rossi’s point of view, form stands only on physical basis rather than ritual. Also, He has reduced typology exclusively to the field of urban analysis. For Rossi, empty form has become the essence of architecture. In the other hand, some researchers believe, type is necessary as a remembering device for architecture. Its record is the history and the collective human memory of architecture. The essence of architecture transcends its builders time or era. Society demands a historical continuity in architecture for its cultural framework and for the lessons learned in building techniques. The notion of type then, can be seen as a method of historical continuity in architecture that links the past to the future, and with its surrounding context and culture.
This study seeks to find the true meaning and historical evidence-based definition of type and typology, which allows the presence of physical body and metaphysical aspects (architectural backgrounds, experiences, architects, building residents and non-material concepts) together. In this paper, the analytical – descriptive methods is utilized to introduce and criticize the contemporary ideas and a proposed definition of type as an abstract image constructed by physical body and scheme, is presented. Considering the proposed definition of type and typology, Talardar houses, as a type of vernacular houses in Taft city will be analyzed. Finally, because of biological history and formal concept of "type and typology", the term of "Dastgāh" (Architectural Modal System) is proposed. In the other words, due to type’s nature, term of “architectural modal system” is closer and more appropriate for the word of type in architecture. In an architectural modal system, the material and non-material aspects have attended as mass and space language. In addition, the architectural modal system can be presented as a national model system and vernacular modal system such as: musical modal system that on a national scale has limited number, but on a local scale with a scheme of national modal system, according to place and time to take a unique form. The ability to identify unique aspects of national and vernacular modal system as well as boundaries of diverse architecture in the different regions is an outstanding feature of this definition and proposed method of type and typology.