Volume of a @C01281@ of a mixture divided by the sum of volumes of all constituents prior to mixing.
See:
fractions
Sources: Green Book, 2nd ed., p. 41 [Terms] [Book] PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 998 [Terms] [Paper]