Final answer:
Shotguns are classified by gauge, a term referring to the diameter of the shotgun bore and corresponding shell size, not to be confused with architectural designs or rifling in barrels of rifles and cannons.
Step-by-step explanation:
Shotguns are classified by gauge, which is a measure related to the diameter of the smooth shotgun bore and the size of the shot-shell designed for that bore. Gauge is an important factor in firearms, especially when discussing the capabilities and purposes of different shotgun types. Unlike the information about shotgun houses, the gauge of a shotgun directly relates to its design and use in shooting, not to be confused with housing architecture or cadastral systems. While rifling is related to firearms such as rifles and cannons, it refers to the grooves in the barrel that causes a bullet to spin, which is distinct from the shotgun's smooth bore.