In disciplinary linguistics, indexicality is studied in the subdiscipline of pragmatics. Cultural ecology as developed by Steward is a major subdiscipline of anthropology. It is a subfield of arachnology, a subdiscipline of the field of zoology. This phenomenon is part of pragmatics, a subdiscipline of linguistics. The academic discipline of second-language acquisition is a subdiscipline of applied linguistics. Plant physiology is a subdiscipline of botany concerned with the functioning of plants. It is also a subdiscipline of sociology that studies evolution of social systems. Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Most recently, evolutionary physiology has become a distinct subdiscipline. Cardiac electrophysiology is a relatively young subdiscipline of cardiology and internal medicine. Geographers are historically known for making maps, the subdiscipline of geography known as cartography. By 1890 lunar photography had become a recognized subdiscipline of astronomy. Fluid mechanics is a subdiscipline of continuum mechanics, as illustrated in the following table. HVAC (heating, ventilation, and air conditioning) is a major subdiscipline of mechanical engineering. This is a subdiscipline of food science.