A value of Aspect Property (also stative aspect) assigned to the designated element in the clause when the meaning selected for the clause is that which indicates that the situation spoken about has internal temporal structure, it cannot be regarded as habitual, but is regarded as a continuing state. Hence, Nonprogressive Aspect can be regarded as a sub-type of continuousness (which, in turn, is a sub-type of imperfectivity). Since languages have different criteria for classifying predicates as stative or not, they may have different rules for determining when explicitly nonprogressive (i.e. explicitly stative) forms can be used.
Typically, for an aspect value to be labelled as Nonprogressive, the aspectual meaning has to minimally express nonprogressiveness, although it may additionally express other temporal, aspectual, or modal meanings, or actionality distinctions. [Kibort 2008c: 8]