Table 1.

The Pittsburgh Model of Function as it relates to describing the function of any given ncRNA. The functional classification beings with the defined occurrence of a ncRNA (expression) and sequentially increases in the level of the classification based on the type of functional information garnered from studying the ncRNA in its biological system

Classification/meaning	Definition
Vague	Insufficient evidence to infer one or more meanings of function within this model, nor to derive a new meaning
Expression	The presence or amount of ncRNA transcript
Capacities	Intrinsic physical properties of ncRNA; the necessity of the object’s behavior given an environment (e.g., structural constraints)
Interactions	Physical contacts, direct or indirect, between the ncRNA and the other components of a system
Physiological Implications	The ncRNA’s involvement in biological processes as enabled by a set of its capacities, interactions, and expression patterns, independent of cross-generational considerations.
Evolutionary Implications	The ncRNA’s influence on population dynamics over successive generations, as enabled by its physiological implications and their interplay with environmental pressures.