A vector quantity the scalar product of which with the cross sectional area vector is equal to the @E01927@. By magnitude it is the @E01927@ divided by the cross sectional area.
Green Book, 2nd ed., p. 14 [Terms] [Book]
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 971 [Terms] [Paper]