fractional change of a quantity

https://doi.org/10.1351/goldbook.F02495
A term which may be expressed infinitesimally at time t by the differential dQ(t)Q(t). For a finite time interval the quotient is ΔQ(t1;t2)Q(t1)=[Q(t2)Q(t1)]Q(t1) The quantities Q(t1) and Q(t2) are of the same kind and have the same type of component. Fractional change has dimension one. Examples are: mass fractional change, dm(t)m(t);
amount of substance
fractional change, dn(t)n(t).
Source:
PAC, 1992, 64, 1569. (Quantities and units for metabolic processes as a function of time (IUPAC Recommendations 1992)) on page 1571 [Terms] [Paper]